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Pharaoh 2019 Mol Neurobiol + (Age-related decline in circulating levels … Age-related decline in circulating levels of insulin-like growth factor (IGF)-1 is associated with reduced cognitive function, neuronal aging, and neurodegeneration. Decreased mitochondrial function along with increased reactive oxygen species (ROS) and accumulation of damaged macromolecules are hallmarks of cellular aging. Based on numerous studies indicating pleiotropic effects of IGF-1 during aging, we compared the central and peripheral effects of circulating IGF-1 deficiency on tissue mitochondrial function using an inducible liver IGF-1 knockout (LID). Circulating levels of IGF-1 (~ 75%) were depleted in adult male Igf1f/f mice via AAV-mediated knockdown of hepatic IGF-1 at 5 months of age. Cognitive function was evaluated at 18 months using the radial arm water maze and glucose and insulin tolerance assessed. Mitochondrial function was analyzed in hippocampus, muscle, and visceral fat tissues using high-resolution respirometry O2K as well as redox status and oxidative stress in the cortex. Peripherally, IGF-1 deficiency did not significantly impact muscle mass or mitochondrial function. Aged LID mice were insulin resistant and exhibited ~ 60% less adipose tissue but increased fat mitochondrial respiration (20%). The effects on fat metabolism were attributed to increases in growth hormone. Centrally, IGF-1 deficiency impaired hippocampal-dependent spatial acquisition as well as reversal learning in male mice. Hippocampal mitochondrial OXPHOS coupling efficiency and cortex ATP levels (~ 50%) were decreased and hippocampal oxidative stress (protein carbonylation and F2-isoprostanes) was increased. These data suggest that IGF-1 is critical for regulating mitochondrial function, redox status, and spatial learning in the central nervous system but has limited impact on peripheral (liver and muscle) metabolism with age. Therefore, IGF-1 deficiency with age may increase sensitivity to damage in the brain and propensity for cognitive deficits. Targeting mitochondrial function in the brain may be an avenue for therapy of age-related impairment of cognitive function. Regulation of mitochondrial function and redox status by IGF-1 is essential to maintain brain function and coordinate hippocampal-dependent spatial learning. While a decline in IGF-1 in the periphery may be beneficial to avert cancer progression, diminished central IGF-1 signaling may mediate, in part, age-related cognitive dysfunction and cognitive pathologies potentially by decreasing mitochondrial function.gies potentially by decreasing mitochondrial function.)
Egerman 2015 Cell Metab + (Age-related frailty may be due to decrease … Age-related frailty may be due to decreased skeletal muscle regeneration. The role of TGF-β molecules myostatin and GDF11 in regeneration is unclear. Recent studies showed an age-related decrease in GDF11 and that GDF11 treatment improves muscle regeneration, which were contrary to prior studies. We now show that these recent claims are not reproducible and the reagents previously used to detect GDF11 are not GDF11 specific. We develop a GDF11-specific immunoassay and show a trend toward increased GDF11 levels in sera of aged rats and humans. GDF11 mRNA increases in rat muscle with age. Mechanistically, GDF11 and myostatin both induce SMAD2/3 phosphorylation, inhibit myoblast differentiation, and regulate identical downstream signaling. GDF11 significantly inhibited muscle regeneration and decreased satellite cell expansion in mice. Given early data in humans showing a trend for an age-related increase, GDF11 could be a target for pharmacologic blockade to treat age-related sarcopenia. blockade to treat age-related sarcopenia.)
Andersson 2011 Cell Metab + (Age-related loss of muscle mass and force … Age-related loss of muscle mass and force (sarcopenia) contributes to disability and increased mortality. Ryanodine receptor 1 (RyR1) is the skeletal muscle sarcoplasmic reticulum calcium release channel required for muscle contraction. RyR1 from aged (24 months) rodents was oxidized, cysteine-nitrosylated, and depleted of the channel-stabilizing subunit calstabin1, compared to RyR1 from younger (3-6 months) adults. This RyR1 channel complex remodeling resulted in "leaky" channels with increased open probability, leading to intracellular calcium leak in skeletal muscle. Similarly, 6-month-old mice harboring leaky RyR1-S2844D mutant channels exhibited skeletal muscle defects comparable to 24-month-old wild-type mice. Treating aged mice with S107 stabilized binding of calstabin1 to RyR1, reduced intracellular calcium leak, decreased reactive oxygen species (ROS), and enhanced tetanic Ca(2+) release, muscle-specific force, and exercise capacity. Taken together, these data indicate that leaky RyR1 contributes to age-related loss of muscle function.es to age-related loss of muscle function.)
Joseph 2012 Aging Cell + (Age-related loss of muscle mass and streng … Age-related loss of muscle mass and strength (sarcopenia) leads to a decline in physical function and frailty in the elderly. Among the many proposed underlying causes of sarcopenia, mitochondrial dysfunction is inherent in a variety of aged tissues. The intent of this study was to examine the effect of aging on key groups of regulatory proteins involved in mitochondrial biogenesis and how this relates to physical performance in two groups of sedentary elderly participants, classified as high- and low-functioning based on the Short Physical Performance Battery test. Muscle mass was decreased by 38% and 30% in low-functioning elderly (LFE) participants when compared to young and high-functioning elderly (HFE) participants, respectively, and positively correlated to physical performance. Mitochondrial respiration in permeabilized muscle fibers was reduced (41%) in the LFE group when compared to the young, and this was associated with a 30% decline in COX activity. Levels of key metabolic regulators, SIRT3 and [[PGC-1α]] were significantly reduced (50%) in both groups of elderly participants when compared to young. Similarly, the fusion protein OPA1 was lower in muscle from elderly subjects, however no changes were detected in Mfn2, Drp1 or Fis1 among the groups. In contrast, protein import machinery (PIM) components Tom22 and cHsp70 were increased in the LFE group when compared to the young. This study suggests that aging in skeletal muscle is associated with impaired mitochondrial function and altered biogenesis pathways, and that this may contribute to muscle atrophy and the decline in muscle performance observed in the elderly population.rmance observed in the elderly population.)
Ahn 2018 Redox Biol + (Age-related loss of skeletal muscle mass and contractile dysfunction, or sarcopenia, reduces independence and quality of life in the elderly and leads to increased risk of comorbidities...)
Ahn 2022 Aging Cell + (Age-related muscle atrophy and weakness, o … Age-related muscle atrophy and weakness, or sarcopenia, are significant contributors to compromised health and quality of life in the elderly. While the mechanisms driving this pathology are not fully defined, reactive oxygen species, neuromuscular junction (NMJ) disruption, and loss of innervation are important risk factors. The goal of this study is to determine the impact of mitochondrial hydrogen peroxide on neurogenic atrophy and contractile dysfunction. Mice with muscle-specific overexpression of the mitochondrial H2O2 scavenger peroxiredoxin3 (mPRDX3) were crossed to Sod1KO mice, an established mouse model of sarcopenia, to determine whether reduced mitochondrial H2O2 can prevent or delay the redox-dependent sarcopenia. Basal rates of H2O2 generation were elevated in isolated muscle mitochondria from Sod1KO, but normalized by mPRDX3 overexpression. The mPRDX3 overexpression prevented the declines in maximum mitochondrial oxygen consumption rate and calcium retention capacity in Sod1KO. Muscle atrophy in Sod1KO was mitigated by ~20% by mPRDX3 overexpression, which was associated with an increase in myofiber cross-sectional area. With direct muscle stimulation, maximum isometric specific force was reduced by ~20% in Sod1KO mice, and mPRDX3 overexpression preserved specific force at wild-type levels. The force deficit with nerve stimulation was exacerbated in Sod1KO compared to direct muscle stimulation, suggesting NMJ disruption in Sod1KO. Notably, this defect was not resolved by overexpression of mPRDX3. Our findings demonstrate that muscle-specific PRDX3 overexpression reduces mitochondrial H2O2 generation, improves mitochondrial function, and mitigates loss of muscle quantity and quality, despite persisting NMJ impairment in a murine model of redox-dependent sarcopenia.ion, and mitigates loss of muscle quantity and quality, despite persisting NMJ impairment in a murine model of redox-dependent sarcopenia.)
Paeaesuke 2015 Oxid Med Cell Longev + (Ageing is associated with suppressed regen … Ageing is associated with suppressed regenerative potential of muscle precursor cells due to decrease of satellite cells and suppressive intramuscular milieu on their activation, associated with ageing-related low-grade inflammation. The aim of the study was to characterize the function of oxidative phosphorylation (OXPHOS), glycolysis, adenylate kinase (AK), and creatine kinase (CK)-mediated systems in young and older individuals.Myoblasts were cultivated from biopsies taken by transcutaneous conchotomy from ''vastus lateralis'' muscle in young (20-29 yrs, n=7) and older (70-79 yrs, n=7) subjects. Energy metabolism was assessed in passages 2 to 6 by oxygraphy and enzyme analysis.In myoblasts of young and older subjects the rate of OXPHOS decreased during proliferation from passage 2 to 6. The total activities of CK and AK decreased. Myoblasts of passage 2 cultivated from young muscle showed higher rate of OXPHOS and activities of CK and AK compared to myoblasts from older subjects while hexokinase and pyruvate kinase were not affected by ageing.Proliferation of myoblasts ''in vitro'' is associated with down-regulation of OXPHOS and energy storage and transfer systems. Ageing ''in vivo'' exerts an impact on satellite cells which results in altered metabolic profile in favour of the prevalence of glycolytic pathways over mitochondrial OXPHOS of myoblasts.ys over mitochondrial OXPHOS of myoblasts.)
Paju 2014 Abstract MiP2014 + (Ageing is frequently associated with sarco … Ageing is frequently associated with sarcopenia, which has been attributed to low grade inflammation, suppressed regenerative potential of muscle precursor cells and homeostatic changes in the niches of satellite cells of old persons [1,2]. The aim of this study was to investigate mitochondrial function in primary cell cultures, derived from biopsies taken from young and old individuals.Primary muscle cell culture myoblasts, obtained from biopsies of vastus lateralis in young (19-29 y) and old (70-80 y) subjects, were purified with CD56 antibody microbeads on MACS and cultured in the presence of HGF. The cultures were stimulated with differentiation media supplement, insulin-transferrin-sodium selenite (ITS), for 6 days with one of cytokines IL1, IL6 or TNF-α. The function of respiratory complexes (OXPHOS) was assessed by high-resolution respirometry.The myoblasts cultivated from old individuals differentiated into myotubes markedly slower than myoblasts from young individuals in ITS medium (''P''<0.0001). The effect of IL-6 depended on donor age, as its effect on myoblast differentiation decreased with age. Treatment of human myoblasts with TNF-α and IL-1β increased the proliferation and blocked differentiation in the presence of ITS. The inhibitory effect of TNF-α and IL-1β on myotubes formation was mediated by down-regulation of mRNA levels of myogenin and muscle-specific isoforms of CK (CKM and CKMT2). The data on mitochondrial respiration revealed that IL-1β caused a significant decrease in mitochondrial Complex I- and II-linked respiration, normalized on cell protein content both in the myotubes of old and young individuals. This action of IL1-β was not seen when the respiratory results were normalized on citrate synthase activity, revealing the role of a decrease in mitochondrial content in these cells. TNF-α, on the contrary, caused a significant increase in mitochondrial Complex I- and II-linked respiration, normalized on protein in myotubes of old and young subjects. This action of TNF-α remained significant when respiration was normalized on citrate synthase activity. The mode of action of these pro-inflammatory cytokines on OXPHOS of muscle cell cultures was the same in both groups, young and old persons.Our data suggest that the myoblasts cultivated from biopsies of old individuals differentiate into myotubes slower than those from young individuals. The actions of pro-inflammatory cytokines on OXPHOS level of these cell cultures are different: IL-1β decreased, TNF-α stimulated but IL-6 exerted no alteration on OXPHOS activity, both in old or young individuals. The OXPHOS capacity in myogenic cell culture depends more on the mode of action of cytokine than the donor’s age.e of action of cytokine than the donor’s age.)
Gnaiger 2012 Abstract-FEPS-Santiago de Compostela + (Aging implicates a progressive decline in … Aging implicates a progressive decline in muscle mass and strength (sarcopenia) which is counteracted by strength training, and a decline of aerobic performance (muscle fatigability, reduced aerobic capacity and loss of mitochondrial power or OXPHOS capacity in muscle tissue). OXPHOS capacity is increased or maintained high by a life style involving endurance exercise and strength training [1]. Life style changes from the age of 20-30 years to the elderly, but is subject to change and intervention. Depending on group selection in cross-sectional studies, OXPHOS capacity declines from the age of 20-30 years [2,3], or is independent of age up to 80 years [4,5]. Independent of age, there is a strong decline of OXPHOS capacity in human vastus lateralis from BMI of 20 to 30 [6]. The relationship between BMI, training and OXPHOS capacity is also observed in horse skeletal muscle [7]. At a BMI >30, a minimum OXPHOS capacity is reached in human v. lateralis that may be characteristic of a low-grade inflammatory state (‘mitochondrial fever’). Onset of degenerative diseases (diabetes 2, neuromuscular degeneration, various cancers) and mitochondrial dysfunction interact in an amplification loop progressing slowly with age, such that cause and effect of mitochondrial dysfunction cannot be distinguished. Diminished antioxidant capacity at low mitochondrial density is an important mechanistic candidate in the state of mitochondrial fever.Contribution to K-Regio ''[[MitoCom_O2k-Fluorometer|MitoCom Tyrol]]''. # [[Pesta_2011_Am J Physiol Regul Integr Comp Physiol|Pesta D, Hoppel F, Macek C, Messner H, Faulhaber M, Kobel C, Parson W, Burtscher M, Schocke M, Gnaiger E (2011) Similar qualitative and quantitative changes of mitochondrial respiration following strength and endurance training in normoxia and hypoxia in sedentary humans. Am J Physiol Regul Integr Comp Physiol 301:R1078–87.]]# Short KR, Bigelow ML, Kahl J, Singh R, Coenen-Schimke J, Raghavakaimal S, Nair KS (2005) Decline in skeletal muscle mitochondrial function with aging in humans. Proc Natl Acad Sci U S A 102:5618-23.# [[Joseph 2012 Aging Cell|Joseph AM, Adhihetty PJ, Buford TW, Wohlgemuth SE, Lees HA, Nguyen LM, Aranda JM, Sandesara BD, Pahor M, Manini TM, Marzetti E, Leeuwenburgh C (2012) The impact of aging on mitochondrial function and biogenesis pathways in skeletal muscle of sedentary high- and low-functioning elderly individuals. Aging Cell 11:801-9.]]# Lanza IR, Short DK, Short KR, Raghavakaimal S, Basu R, Joyner MJ, McConnell JP, Nair KS (2008) Endurance exercise as a countermeasure for aging. Diabetes 57:2933-42.# [[Larsen 2012 Acta Physiol (Oxf)|Larsen S, Hey-Mogensen M, Rabol R, Stride N, Helge JW, Dela F (2012) The influence of age and aerobic fitness: Effects on mitochondrial respiration in skeletal muscle. Acta Physiol (Oxf) 205:423-32.]]# [[Gnaiger 2009 Int J Biochem Cell Biol|Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int J Biochem Cell Biol 41:1837–45.]]# [[Votion_2012_PLoS One|Votion DM, Gnaiger E, Lemieux H, Mouithys-Mickalad A, Serteyn D (2012) Physical fitness and mitochondrial respiratory capacity in horse skeletal muscle. PLoS One 7:e34890.]]_2012_PLoS One|Votion DM, Gnaiger E, Lemieux H, Mouithys-Mickalad A, Serteyn D (2012) Physical fitness and mitochondrial respiratory capacity in horse skeletal muscle. PLoS One 7:e34890.]])
Reis 2016 Aging (Albany NY) + (Aging increases the risk of type 2 diabete … Aging increases the risk of type 2 diabetes, and this can be prevented by dietary restriction (DR). We have previously shown that DR inhibits the downregulation of miRNAs and their processing enzymes - mainly Dicer - that occurs with aging in mouse white adipose tissue (WAT). Here we used fat-specific Dicer knockout mice (AdicerKO) to understand the contributions of adipose tissue Dicer to the metabolic effects of aging and DR. Metabolomic data uncovered a clear distinction between the serum metabolite profiles of Lox control and AdicerKO mice, with a notable elevation of branched-chain amino acids (BCAA) in AdicerKO. These profiles were associated with reduced oxidative metabolism and increased lactate in WAT of AdicerKO mice and were accompanied by structural and functional changes in mitochondria, particularly under DR. AdicerKO mice displayed increased mTORC1 activation in WAT and skeletal muscle, where Dicer expression is not affected. This was accompanied by accelerated age-associated insulin resistance and premature mortality. Moreover, DR-induced insulin sensitivity was abrogated in AdicerKO mice. This was reverted by rapamycin injection, demonstrating that insulin resistance in AdicerKO mice is caused by mTORC1 hyperactivation. Our study evidences a DR-modulated role for WAT Dicer in controlling metabolism and insulin resistance.rolling metabolism and insulin resistance.)
Gregg 2016 Diabetes + (Aging is accompanied by impaired glucose h … Aging is accompanied by impaired glucose homeostasis and an increased risk of type 2 diabetes, culminating in the failure of insulin secretion from pancreatic β cells. To investigate the effects of age on β cell metabolism, we established a novel assay to directly image islet metabolism using NAD(P)H fluorescence lifetime imaging (FLIM). We determined that impaired mitochondrial activity underlies an age-dependent loss of insulin secretion in human islets. NAD(P)H FLIM revealed a comparable decline in mitochondrial function in the pancreatic islets of aged mice (≥ 24 months), resulting from 52% and 57% defects in flux through complex I and II of the electron transport chain. However, insulin secretion and glucose tolerance are preserved in aged mouse islets by the heightened metabolic sensitivity of the β cell triggering pathway, an adaptation clearly encoded in the metabolic and Ca2+ oscillations that trigger insulin release (Ca2+ plateau fraction: young, 0.211 ± 0.006; aged, 0.380 ± 0.007, P < 0.0001). This enhanced sensitivity is driven by a reduction in KATP channel conductance (diazoxide: young, 5.1 ± 0.2 nS; aged, 3.5 ± 0.5 nS, P < 0.01), resulting in a ∼2.8 mM left shift in the β cell glucose threshold. Our results demonstrate how mice, but not humans, are able to successfully compensate for age-associated metabolic dysfunction by adjusting their β cell glucose sensitivity, and highlight an essential mechanism for ensuring the maintenance of insulin secretion.© 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.perly cited, the use is educational and not for profit, and the work is not altered.)
Goetzman 2023 Antioxidants (Basel) + (Aging is associated with a decline in mito … Aging is associated with a decline in mitochondrial function which may contribute to age-related diseases such as neurodegeneration, cancer, and cardiovascular diseases. Recently, mitochondrial Complex II has emerged as an important player in the aging process. Mitochondrial Complex II converts succinate to fumarate and plays an essential role in both the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC). The dysfunction of Complex II not only limits mitochondrial energy production; it may also promote oxidative stress, contributing, over time, to cellular damage, aging, and disease. Intriguingly, succinate, the substrate for Complex II which accumulates during mitochondrial dysfunction, has been shown to have widespread effects as a signaling molecule. Here, we review recent advances related to understanding the function of Complex II, succinate signaling, and their combined roles in aging and aging-related diseases.roles in aging and aging-related diseases.)
Eisenberg 2016 Nat Med + (Aging is associated with an increased risk … Aging is associated with an increased risk of cardiovascular disease and death. Here we show that oral supplementation of the natural polyamine spermidine extends the lifespan of mice and exerts cardioprotective effects, reducing cardiac hypertrophy and preserving diastolic function in old mice. Spermidine feeding enhanced cardiac autophagy, mitophagy and mitochondrial respiration, and it also improved the mechano-elastical properties of cardiomyocytes ''in vivo'', coinciding with increased titin phosphorylation and suppressed subclinical inflammation. Spermidine feeding failed to provide cardioprotection in mice that lack the autophagy-related protein Atg5 in cardiomyocytes. In Dahl salt-sensitive rats that were fed a high-salt diet, a model for hypertension-induced congestive heart failure, spermidine feeding reduced systemic blood pressure, increased titin phosphorylation and prevented cardiac hypertrophy and a decline in diastolic function, thus delaying the progression to heart failure. In humans, high levels of dietary spermidine, as assessed from food questionnaires, correlated with reduced blood pressure and a lower incidence of cardiovascular disease. Our results suggest a new and feasible strategy for protection against cardiovascular disease.protection against cardiovascular disease.)
Boushel 2014 Pro Can Soc Exercise Physiol + (Aging is associated with diminished cardio … Aging is associated with diminished cardiovascular function and sarcopenia, and loss of muscle oxidative capacity is considered a salient feature of aging. While moderate-to-high intensity training evokes mitochondrial biogenesis in skeletal muscle, it remains unclear to what extent aging in itself or rather a lower training stimulus that accompanies aging contributes to loss of skeletal muscle mitochondrial function. To address this question leg muscle mitochondrial respiratory capacity in 8 older men (65±2 yrs) who had maintained road cycling training 200 km/week for 50 years was compared to that of 8 age-matched sedentary (UT) controls (67±1 yrs).V˙ O2 max was measured on a bicycle ergometer and a biopsy obtained from vastus lateralis muscle was permeabilized and prepared for high resolution respirometry (Oxygraph, Oroboros, AT). V˙ O2 max was substantially higher (p<0.05) in lifelong trained (45±2 ml/kg/min) compared to UT (27±2 ml/kg/min). Mitochondrial LEAK respiration was higher in ET, and Vmax of mitochondrial respiration (OXPHOS) with mixed substrates was 2-fold higher in the ET (132±6 pmol/sec/mg) compared to UT (72±4 pmol/sec/mg, p<0.01). Higher fatty acid oxidation and substrate control ratios in ET indicate regulatory changes in mitochondria in addition to a larger mitochondrial volume. The findings indicate that skeletal muscle mitochondrial respiratory capacity of ‘lifelong trained’ older males is retained at a level comparable to young athletic individuals, and suggest that decrements in aerobic performance with age are primarily attributed to diminished cardiovascular function.ttributed to diminished cardiovascular function.)
Rufini 2012 Genes Dev + (Aging is associated with impaired scavengi … Aging is associated with impaired scavenging of reactive oxygen species (ROS). Here, we show that TAp73, a p53 family member, protects against aging by regulating mitochondrial activity and preventing ROS accumulation. TAp73-null mice show more pronounced aging with increased oxidative damage and senescence. TAp73 deletion reduces cellular ATP levels, oxygen consumption, and mitochondrial complex IV activity, with increased ROS production and oxidative stress sensitivity. We show that the mitochondrial complex IV subunit cytochrome C oxidase subunit 4 (Cox4i1) is a direct TAp73 target and that Cox4i1 knockdown phenocopies the cellular senescence of TAp73-null cells. Results indicate that TAp73 affects mitochondrial respiration and ROS homeostasis, thus regulating aging.nd ROS homeostasis, thus regulating aging.)
No 2020 Pflugers Arch + (Aging is associated with vulnerability to … Aging is associated with vulnerability to cardiovascular diseases, and mitochondrial dysfunction plays a critical role in cardiovascular disease pathogenesis. Exercise training is associated with benefits against chronic cardiac diseases. The purpose of this study was to determine the effects of aging and treadmill exercise training on mitochondrial function and apoptosis in the rat heart. Fischer 344 rats were divided into young sedentary (YS; ''N'' = 10, 4 months), young exercise (YE; n''N''= 10, 4 months), old sedentary (OS; ''N'' = 10, 20 months), and old exercise (OE; ''N'' = 10, 20 months) groups. Exercise training groups ran on a treadmill at 15 m/min (young) or 10 m/min (old), 45 min/day, 5 days/week for 8 weeks. Morphological parameters, mitochondrial function, mitochondrial dynamics, mitophagy, and mitochondria-mediated apoptosis were analyzed in cardiac muscle. Mitochondrial O2 respiratory capacity and Ca2+ retention capacity gradually decreased, and mitochondrial H2O2 emitting potential significantly increased with aging. Exercise training attenuated aging-induced mitochondrial H2O2 emitting potential and mitochondrial O2 respiratory capacity, while protecting Ca2+ retention in the old groups. Aging triggered imbalanced mitochondrial dynamics and excess mitophagy, while exercise training ameliorated the aging-induced imbalance in mitochondrial dynamics and excess mitophagy. Aging induced increase in Bax and cleaved caspase-3 protein levels, while decreasing Bcl-2 levels. Exercise training protected against the elevation of apoptotic signaling markers by decreasing Bax and cleaved caspase-3 and increasing Bcl-2 protein levels, while decreasing the Bax/Bcl-2 ratio and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive myonuclei. These data demonstrate that regular exercise training prevents aging-induced impairment of mitochondrial function and mitochondria-mediated apoptosis in cardiac muscles.ular exercise training prevents aging-induced impairment of mitochondrial function and mitochondria-mediated apoptosis in cardiac muscles.)
Daum 2013 Proc Natl Acad Sci U S A + (Aging is one of the most fundamental, yet … Aging is one of the most fundamental, yet least understood biological processes that affect all forms of eukaryotic life. Mitochondria are intimately involved in aging, but the underlying molecular mechanisms are largely unknown. Electron cryotomography of whole mitochondria from the aging model organism ''Podospora anserina'' revealed profound age-dependent changes in membrane architecture. With increasing age, the typical cristae disappear and the inner membrane vesiculates. The ATP synthase dimers that form rows at the cristae tips dissociate into monomers in inner-membrane vesicles, and the membrane curvature at the ATP synthase inverts. Dissociation of the ATP synthase dimer may involve the peptidyl prolyl isomerase cyclophilin D. Finally, the outer membrane ruptures near large contact-site complexes, releasing apoptogens into the cytoplasm. Inner-membrane vesiculation and dissociation of ATP synthase dimers would impair the ability of mitochondria to supply the cell with sufficient ATP to maintain essential cellular functions. to maintain essential cellular functions.)
Tyrrell 2019 Circ Res + (Aging is one of the strongest risk factors … Aging is one of the strongest risk factors for atherosclerosis. Yet whether aging increases the risk of atherosclerosis independently of chronic hyperlipidemia is not known. The objective was to determine if vascular aging prior to the induction of hyperlipidemia enhances atherogenesis. We analyzed the aortas of young and aged normolipidemic wild type (WT), disease free mice and found that aging led to elevated IL-6 levels and mitochondrial dysfunction, associated with increased mitophagy and the associated protein Parkin. In aortic tissue culture, we found evidence that with aging mitochondrial dysfunction and IL-6 exist in a positive feedback loop. We triggered acute hyperlipidemia in aged and young mice by inducing liver-specific degradation of the LDL receptor combined with a 10-week western diet and found that atherogenesis was enhanced in aged WT mice. Hyperlipidemia further reduced mitochondrial function and increased the levels of Parkin in the aortas of aged mice but not young mice. Genetic disruption of autophagy in smooth muscle cells of young mice exposed to hyperlipidemia led to increased aortic Parkin and IL-6 levels, impaired mitochondrial function, and enhanced atherogenesis. Importantly, enhancing mitophagy in aged, hyperlipidemic mice via oral administration of spermidine prevented the increase in aortic IL-6 and Parkin, attenuated mitochondrial dysfunction, and reduced atherogenesis.Prior to hyperlipidemia, aging elevates IL-6 and impairs mitochondrial function within the aorta, associated with enhanced mitophagy and increased Parkin levels. These age-associated changes prime the vasculature to exacerbate atherogenesis upon acute hyperlipidemia. Our work implies that novel therapeutics aimed at improving vascular mitochondrial bioenergetics or reducing inflammation before hyperlipidemia may reduce age-related atherosclerosis.ia may reduce age-related atherosclerosis.)
Shields 2021 Front Cell Dev Biol + (Aging is the greatest risk factor for a mu … Aging is the greatest risk factor for a multitude of diseases including cardiovascular disease, neurodegeneration and cancer. Despite decades of research dedicated to understanding aging, the mechanisms underlying the aging process remain incompletely understood. The widely-accepted free radical theory of aging (FRTA) proposes that the accumulation of oxidative damage caused by reactive oxygen species (ROS) is one of the primary causes of aging. To define the relationship between ROS and aging, there have been two main approaches: comparative studies that measure outcomes related to ROS across species with different lifespans, and experimental studies that modulate ROS levels within a single species using either a genetic or pharmacologic approach. Comparative studies have shown that levels of ROS and oxidative damage are inversely correlated with lifespan. While these studies in general support the FRTA, this type of experiment can only demonstrate correlation, not causation. Experimental studies involving the manipulation of ROS levels in model organisms have generally shown that interventions that increase ROS tend to decrease lifespan, while interventions that decrease ROS tend to increase lifespan. However, there are also multiple examples in which the opposite is observed: increasing ROS levels results in extended longevity, and decreasing ROS levels results in shortened lifespan. While these studies contradict the predictions of the FRTA, these experiments have been performed in a very limited number of species, all of which have a relatively short lifespan. Overall, the data suggest that the relationship between ROS and lifespan is complex, and that ROS can have both beneficial or detrimental effects on longevity depending on the species and conditions. Accordingly, the relationship between ROS and aging is difficult to generalize across the tree of life.ult to generalize across the tree of life.)
Dawson 2020 Exp Gerontol + (Aging is typically associated with a decli … Aging is typically associated with a decline in whole animal performance that ultimately contributes to death. It is suspected that a decline in ATP production leads to dysfunction in cellular processes, contributing to the decline in performance. Birds require large amounts of ATP to support physiological process, especially flight, which is one of the most energetically expensive forms of locomotion in the animal kingdom to sustain. Since the bulk of ATP production is coordinated through mitochondrial activity, we set out to explore mitochondrial function in young (~8 months) and old (~73 months) zebra finches (''Taeniopygia guttata''). We exploited the fact that avian red blood cells (RBCs) are nucleated and have functional mitochondria to explore the phenomenon of age-related decline in mitochondrial function without the need for terminal sampling. We found that RBCs from old zebra finches have lower flux control ratios (mitochondrial O2 consumption attributed to ATP production; 0.29-0.36-fold), exhibit higher respiration (1.4-fold), and significantly higher citrate synthase activity (1.4-fold) than young birds. Respiration rates normalized to citrate synthase activity suggest that mitochondrial quality is changing, as leak state is significantly lower (0.39-fold) in old zebra finches in comparison to young animals. Overall, our findings indicate a possible change in the function of mitochondria in older zebra finches, which may be associated with a corresponding increase in mitochondrial quantity, possibly to offset a decline in mitochondrial quality.Copyright © 2018. Published by Elsevier Inc.mall>Copyright © 2018. Published by Elsevier Inc.)
Pharaoh 2023 Geroscience + (Aging muscle experiences functional declin … Aging muscle experiences functional decline in part mediated by impaired mitochondrial ADP sensitivity. Elamipretide (ELAM) rapidly improves physiological and mitochondrial function in aging and binds directly to the mitochondrial ADP transporter ANT. We hypothesized that ELAM improves ADP sensitivity in aging leading to rescued physiological function. We measured the response to ADP stimulation in young and old muscle mitochondria with ELAM treatment, ''in vivo'' heart and muscle function, and compared protein abundance, phosphorylation, and S-glutathionylation of ADP/ATP pathway proteins. ELAM treatment increased ADP sensitivity in old muscle mitochondria by increasing uptake of ADP through the ANT and rescued muscle force and heart systolic function. Protein abundance in the ADP/ATP transport and synthesis pathway was unchanged, but ELAM treatment decreased protein s-glutathionylation incuding of ANT. Mitochondrial ADP sensitivity is rapidly modifiable. This research supports the hypothesis that ELAM improves ANT function in aging and links mitochondrial ADP sensitivity to physiological function. ELAM binds directly to ANT and ATP synthase and ELAM treatment improves ADP sensitivity, increases ATP production, and improves physiological function in old muscles.ves physiological function in old muscles.)
Bernhardt 2015 Sci Rep + (Aging of biological systems is accompanied … Aging of biological systems is accompanied by degeneration of mitochondrial functions. Different pathways are active to counteract the processes which lead to mitochondrial dysfunction. Mitochondrial dynamics, the fission and fusion of mitochondria, is one of these quality control pathways. Mitophagy, the controlled degradation of mitochondria, is another one. Here we show that these pathways are linked. A double deletion mutant of Saccharomyces cerevisiae in which two essential components of the fission and fusion machinery, Dnm1 and Mgm1, are simultaneously ablated, contain wild-type like filamentous mitochondria, but are characterized by impaired respiration, an increased sensitivity to different stressors, increased mitochondrial protein carbonylation, and a decrease in mitophagy and replicative lifespan. These data show that a balanced mitochondrial dynamics and not a filamentous mitochondrial morphotype per se is the key for a long lifespan and demonstrate a cross-talk between two different mitochondrial quality control pathways.nt mitochondrial quality control pathways.)
Hepple 2014 Abstract MiP2014 + (Aging of skeletal muscle is associated wit … Aging of skeletal muscle is associated with progressive atrophy, reaching clinically relevant thresholds in terms of weakness, mobility impairment and physical frailty in a significant fraction of individuals ≥80 y of age. Amongst the factors posited to be involved, mitochondrial alterations are implicated in the atrophy of aging muscle through recruitment of mitochondrial-mediated pathways of apoptosis and proteolysis. However, denervation is also known to recruit these same mitochondrial pathways. In view of the sporadic denervation that occurs in aging muscle, consideration of denervation’s role in recruitment of mitochondrial atrophy pathways is essential to identify relevant therapeutic targets. As such, this presentation will review our current evidence from human skeletal muscle biopsies across a range of ages and physical activity levels, examining the impact of aging on mitochondrial function and the role played by denervation across this continuum. As will be demonstrated, skeletal muscle mitochondrial alterations in septuagenarian subjects appears to be a primary event unrelated to denervation, where an increased susceptibility to mitochondrial permeability transition persists even in physically active subjects. In contrast, octogenarian subjects exhibit denervation-induced modulation of mitochondrial reactive oxygen species emission, suggesting failed reinnervation rather than mitochondrial dysfunction as a more appropriate therapeutic target when aging muscle atrophy becomes most clinically relevant. atrophy becomes most clinically relevant.)
Soares 2022 Geroscience + (Aging of the vasculature is characterized … Aging of the vasculature is characterized by endothelial dysfunction and arterial stiffening, two key events in the pathogenesis of cardiovascular disease (CVD). Treatment with sodium glucose transporter 2 (SGLT2) inhibitors is now known to decrease cardiovascular morbidity and mortality in type 2 diabetes. However, whether SGLT2 inhibition attenuates vascular aging is unknown. We first confirmed in a cohort of adult subjects that aging is associated with impaired endothelial function and increased arterial stiffness and that these two variables are inversely correlated. Next, we investigated whether SGLT2 inhibition with empagliflozin (Empa) ameliorates endothelial dysfunction and reduces arterial stiffness in aged mice with confirmed vascular dysfunction. Specifically, we assessed mesenteric artery endothelial function and stiffness (via flow-mediated dilation and pressure myography mechanical responses, respectively) and aortic stiffness (''in vivo'' via pulse wave velocity and ''ex vivo'' via atomic force microscopy) in Empa-treated (14 mg/kg/day for 6 weeks) and control 80-week-old C57BL/6 J male mice. We report that Empa-treated mice exhibited improved mesenteric endothelial function compared with control, in parallel with reduced mesenteric artery and aortic stiffness. Additionally, Empa-treated mice had greater vascular endothelial nitric oxide synthase activation, lower phosphorylated cofilin, and filamentous actin content, with downregulation of pathways involved in production of reactive oxygen species. Our findings demonstrate that Empa improves endothelial function and reduces arterial stiffness in a preclinical model of aging, making SGLT2 inhibition a potential therapeutic alternative to reduce the progression of CVD in older individuals.e progression of CVD in older individuals.)
Hagl 2016 Nutr Neurosci + (Aging represents a major risk factor for n … Aging represents a major risk factor for neurodegenerative diseases such as Alzheimer's disease. Mitochondria are significantly involved in both the aging process and neurodegeneration. One strategy to protect the brain and to prevent neurodegeneration is a healthy lifestyle including a diet rich in antioxidants and polyphenols. Rice bran extract (RBE) contains various antioxidants including natural vitamin E forms (tocopherols and tocotrienols) and gamma-oryzanol. In this work, we examined the effects of a stabilized RBE on mitochondrial function in 18-month-old Naval Medical Research Institute mice (340 mg/kg body weight/day), which received the extract for 3 weeks via oral gavage.Mitochondrial parameters were measured using high-resolution respirometry (Oroboros Oxygraph-2k), Western blot analysis, and photometric methods in dissociated brain cells, isolated mitochondria, and brain homogenate. Vitamin E concentrations in blood plasma and brain tissue were measured using HPLC with fluorescence detection. Aging leads to decreased mitochondrial function (decreased mitochondrial respiration and ATP production) and decreased protein expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1alpha). RBE administration increased alpha-tocopherol concentrations in the brain and compensated for age-related mitochondrial dysfunction by increasing mitochondrial respiration, membrane potential, PGC1alpha protein expression, and citrate synthase activity. Furthermore, resistance of brain cells to sodium nitroprusside-induced nitrosative stress was improved. According to these results, RBE is a promising candidate nutraceutical for the prevention of age-related neurodegenerative diseases.of age-related neurodegenerative diseases.)
Hagl 2016 Neuromolecular Med + (Aging represents a major risk factor for t … Aging represents a major risk factor for the development of neurodegenerative diseases like Alzheimer's disease (AD). As mitochondrial dysfunction plays an important role in brain aging and occurs early in the development of AD, the prevention of mitochondrial dysfunction might help to slow brain aging and the development of neurodegenerative diseases. Rice bran extract (RBE) contains high concentrations of vitamin E congeners and γ-oryzanol. We have previously shown that RBE increased mitochondrial function and protected from mitochondrial dysfunction ''in vitro'' and in short-term ''in vivo'' feeding studies. To mimic the use of RBE as food additive, we have now investigated the effects of a long-term (6 months) feeding of RBE on survival, behavior and brain mitochondrial function in aged NMRI mice. RBE administration significantly increased survival and performance of aged NMRI mice in the passive avoidance and Y-maze test. Brain mitochondrial dysfunction found in aged mice was ameliorated after RBE administration. Furthermore, data from mRNA and protein expression studies revealed an up-regulation of mitochondrial proteins in RBE-fed mice, suggesting an increase in mitochondrial content which is mediated by a peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α)-dependent mechanism. Our findings suggest that a long-term treatment with a nutraceutical containing RBE could be useful for slowing down brain aging and thereby delaying or even preventing AD.nd thereby delaying or even preventing AD.)
Reutzel 2018 Oxid Med Cell Longev + (Aging represents a major risk factor for d … Aging represents a major risk factor for developing neurodegenerative diseases such as Alzheimer's disease (AD). As components of the Mediterranean diet, olive polyphenols may play a crucial role in the prevention of AD. Since mitochondrial dysfunction acts as a final pathway in both brain aging and AD, respectively, the effects of a mixture of highly purified olive secoiridoids were tested on cognition and ATP levels in a commonly used mouse model for brain aging. Over 6 months, female NMRI mice (12 months of age) were fed with a blend containing highly purified olive secoiridoids (POS) including oleuropein, hydroxytyrosol and oleurosid standardized for 50 mg oleuropein/kg diet (equivalent to 13.75 mg POS/kg b.w.) or the study diet without POS as control. Mice aged 3 months served as young controls. Behavioral tests showed deficits in cognition in aged mice. Levels of ATP and mRNA levels of NADH-reductase, cytochrome-c-oxidase, and citrate synthase were significantly reduced in the brains of aged mice indicating mitochondrial dysfunction. Moreover, gene expression of Sirt1, CREB, Gap43, and GPx-1 was significantly reduced in the brain tissue of aged mice. POS-fed mice showed improved spatial working memory. Furthermore, POS restored brain ATP levels in aged mice which were significantly increased. Our results show that a diet rich in purified olive polyphenols has positive long-term effects on cognition and energy metabolism in the brain of aged mice.ergy metabolism in the brain of aged mice.)
Lee 2010 Cell Metab + (Aging-associated muscle insulin resistance … Aging-associated muscle insulin resistance has been hypothesized to be due to decreased mitochondrial function, secondary to cumulative free radical damage, leading to increased intramyocellular lipid content. To directly test this hypothesis, we examined both ''in vivo'' and ''in vitro'' mitochondrial function, intramyocellular lipid content, and insulin action in lean healthy mice with targeted overexpression of the human catalase gene to mitochondria (MCAT mice). Here, we show that MCAT mice are protected from age-induced decrease in muscle mitochondrial function (∼30%), energy metabolism (∼7%), and lipid-induced muscle insulin resistance. This protection from age-induced reduction in mitochondrial function was associated with reduced mitochondrial oxidative damage, preserved mitochondrial respiration and muscle ATP synthesis, and AMP-activated protein kinase-induced mitochondrial biogenesis. Taken together, these data suggest that the preserved mitochondrial function maintained by reducing mitochondrial oxidative damage may prevent age-associated whole-body energy imbalance and muscle insulin resistance.y imbalance and muscle insulin resistance.)
Cockova 2017 Thesis + (Aim of this thesis was to observe changes … Aim of this thesis was to observe changes in oxidative metabolism and expression of important neuroenergetic proteins in human neuroblastoma cell line SH-SY5Y due to inhibition of FTO. FTO is a RNA demethylase that uses N6-methyladenosine as substrate. Differences in enzyme expression are connected to a broad area of effects involving energy homeostasis.Mitochondria are the cellular powerhouses, a key elements in production of energy and metabolic substrates, yet a source of potentially dangerous reactive oxygen species (ROS) and analogous reactive molecules. In order to better understand FTO purpose in neuronal energetic metabolism, we examined mitochondrial respiratory chain. Using high-resolution respirometry we were capable of observing impairment in mitochondrial respiration after FTO inhibition. There was a considerable decline in endogenous respiration, maximal respiration rate and reserve capacity. In order to obtain a more detailed view into mitochondrial respiration, expression levels of electron-transport complexes were quantified by Western blot technique. A slight reduction was identified in subunits of complex I and IV. However, the most prominent alteration was seen in the complex II subunit. There were no differences in expression of complex III and ATP synthase subunits. Beside disrupted activity of electron-transport system, ROS production can reflect mitochondrial dysfunction. By using fluorescence probes, we managed to observe increased ROS production in cells treated with FTO inhibitor.Furthermore, we studied how FTO inhibition affects insulin signaling. Expression of selected proteins involved in insulin signaling was detected by Western blot. Increased levels of insulin receptor and insulin degrading enzyme accompanied FTO inhibition. Additionally, a decreased ratio of p-Akt/Akt and p-p38/p38 together with an elevated ratio of p-ERK/ERK was observed. A minimal difference was sighted in PI3K p110 expression or p-GSK3β/GSK3β ratio.Taken together, these results suggest a considerable link between FTO activity and neuronal signaling and metabolic actions. Further research could undoubtedly prove to be beneficial in gaining knowledge about bioenergetics processes in the nervous system.nergetics processes in the nervous system.)
Larsen 2009 Diabetologia + (Aim/hypothesis: The aim of the study was t … Aim/hypothesis: The aim of the study was to investigate mitochondrial function, fibre type distribution and substrate oxidation in arm and leg muscle during exercise in patients with type 2 diabetes and in obese and lean controls.Methods: Indirect calorimetry was used to calculate fat and carbohydrate oxidation during both progressive arm-cranking and leg-cycling exercises. Muscle biopsies from arm and leg were obtained. Fibre type, as well as O2 flux capacity of saponin-permeabilised muscle fibres were measured, the latter by high resolution respirometry, in patients with type 2 diabetes, age- and BMI-matched obese controls, and age-matched lean controls.Results: Fat oxidation was similar in the groups during either arm or leg exercise. During leg exercise at higher intensities, but not during arm exercise, carbohydrate oxidation was lower in patients with type 2 diabetes compared with the other groups. In patients with type 2 diabetes, ADP-stimulated state 3 respiration per mg muscle with parallel electron input from complex I+II was lower in ''m. vastus lateralis'' compared with obese and lean controls, whereas no differences between groups were present in ''m. deltoideus''. A higher percentage of type IIX fibres was seen in ''m. vastus lateralis'' in patients with type 2 diabetes compared with obese and lean controls, whereas no difference was found in the deltoid muscle.Conclusions/interpretation: This study demonstrates similar O2 flux capacity, fibre type distribution and carbohydrate oxidation in arm muscle in the groups despite the presence of attenuated values in leg muscle in patients with type 2 diabetes compared with obese and lean controls.tients with type 2 diabetes compared with obese and lean controls.)
Raboel 2009 J Clin Endocrinol Metabol + (Aim: Skeletal muscle mitochondrial content … Aim: Skeletal muscle mitochondrial content is reduced in type 2 diabetes mellitus (T2DM). Whether hyperglycemia inhibits mitochondrial biogenesis and/or function is unknown. This study examined the effect of different levels of glycemia on skeletal muscle mitochondrial function in patients with T2DM.Patients and Methods: Eleven patients with T2DM [9 males, 2 females; age, 52.8 ± 2.5 yr (mean ± SE); body mass index, 30.2 ± 1.1 kg/m2 ] in poor glycemic control were treated with insulin aspart and NPH insulin for a median period of 46 d (range, 31–59). Mitochondrial respiration and citrate synthase activity (a marker of mitochondrial content) were measured before and after treatment. Eleven healthy subjects (age, 53.3 ± 2.7 yr; body mass index, 30.6 ± 1.1 kg/m2) were included as controls.Results: Hemoglobin A1c (9.1 ± 0.5 to 7.5 ± 0.3%; P < 0.001) and fasting plasma glucose (12.7 ± 1.1 to 6.5 ± 0.3 mmol/liter; P < 0.001) were reduced after treatment. Mitochondrial respiration per milligram muscle was lower in T2DM compared to controls [substrates for complex I, 24% lower (P < 0.05); substrates for complex I+II, 17% lower (P < 0.05)]. Mitochondrial respiration and citrate synthase activity did not differ before and after improvements in glycemic control, but mitochondrial respiration correlated with fasting plasma glucose before (r2 = 0.53; P < 0.05) but not after treatment [r2 = 0.0024; not significant (NS)]. Mitochondrial respiration normalized to mitochondrial content did not differ between control subjects and patients with T2DM.Discussion: Mitochondrial respiration and content was not improved after significant improvements in glycemic control. However, severe hyperglycemia inhibited respiration reversibly, but moderate hyperglycemia and mitochondrial function were not correlated.ration reversibly, but moderate hyperglycemia and mitochondrial function were not correlated.)
Baron 2010 Thesis + (Aim: The aim of this thesis was the analys … Aim: The aim of this thesis was the analysis of copy number variations of themitochondrial DNA (mtDNA) in several tissues and cell types with regard to different mitochondrial associated disorders.Background: The mtDNA copy number can be reduced due to mutations in thenuclear encoded DNA polymerase g (POLG) or damages caused by deleteriousreactive oxygen species (ROS), which are created by the respiratory chain. Thisleads to the insufficient expression of mitochondrial encoded subunits of complexes of the oxidative phosphorylation system (OXPHOS). Consequently an impairment of the biochemical activity and integrity of the cells occurs.Methods: The quantification of the mtDNA was performed by quantitative PCR(qPCR). Biochemical activities were determined by enzymatic assays such as direct measurement of the citrate synthase (CS) activity or comprehensive measurement of the respiratory activity.Results: Mutations in the nuclear inherited gene POLG result in mtDNA depletion in mitochondrial disorders including a mild phenotype of progressive externalophthalmoplegia (PEO) with epilepsy/ataxia. A mtDNA depletion was detected indifferent tissues and cell types of Alpers-Huttenlocher patients with pathogenicnuclear mutations. The mtDNA copy number was reduced in specific hippocampalregions of temporal lobe epilepsy (TLE) patients with Ammons’ horn sclerosis (AHS)accompanied by a decreased CS activity. An ''in vitro'' reduction of the mtDNA in fibroblasts results in an impaired respiratory activity.Conclusions: The mtDNA content is proportional to the mitochondria content andthe energy demand of the respective tissue or cell type under normal conditions. A cell type- and tissue-specific depletion of the mtDNA can be present in several inherited and somatic mitochondrial disorders ''in vivo'' or can be generated by an ''in vitro'' system. The mtDNA depletion diminishes the biochemical activity and integrity of the cells and can contribute to the disease phenotype.d can contribute to the disease phenotype.)
Lai 2019 Acta Physiol (Oxf) + (Aim: The subsarcolemmal (SSM) and interfib … Aim: The subsarcolemmal (SSM) and interfibrillar (IFM) mitochondria in skeletal muscle appear to have distinct biochemical properties affecting metabolism in health and disease. The isolation of mitochondrial subpopulations has been a long-time challenge while the presence of a continuous mitochondrial reticulum challenges the view of distinctive SSM and IFM bioenergetics. Here, a comprehensive approach is developed to identify the best conditions to separate mitochondrial fractions.Methods: The main modifications to the protocol to isolate SSM and IFM from rat skeletal muscle were: (a) decreased dispase content and homogenization speed; (b) trypsin treatment of SSM fractions; (c) recentrifugation of mitochondrial fractions at low speed to remove subcellular components. To identify the conditions preserving mitochondrial function, integrity, and maximizing their recovery, microscopy (light and electron) were used to monitor effectiveness and efficiency in separating mitochondrial subpopulations while respiratory and enzyme activities were employed to evaluate function, recovery, and integrity.Results: With the modifications described, the total mitochondrial yield increased with a recovery of 80% of mitochondria contained in the original skeletal muscle sample. The difference between SSM and IFM oxidative capacity (10%) with complex-I substrate was significant only with a saturated ADP concentration. The inner and outer membrane damage for both subpopulations was <1% and 8%, respectively, while the respiratory control ratio was 16.Conclusion: Using a multidisciplinary approach, conditions were identified to maximize SSM and IFM recovery while preserving mitochondrial integrity, biochemistry, and morphology. High quality and recovery of mitochondrial subpopulations allow to study the relationship between these organelles and disease.ionship between these organelles and disease.)
Hedges IBEC2012 + (Aim: This study aimed to compare mitochond … Aim: This study aimed to compare mitochondrial oxygen consumption in C57BL/6J wild-type and myostatin-deficient mouse soleus and white gastrocnemius muscles.Methods: Muscles were obtained from 4 month-old male mice. Mass-specific oxygen consumption (pmol.O2/mg/sec) was measured in permeabilised muscle, using high-resolution respirometry (Oroboros Oxygraph-2k). Maximal activities of citrate synthase and lactate dehydrogenase were determined by spectrophotometry.Results: Myostatin-deficient soleus (n=6) consumed 20% more oxygen per mg than wild-type soleus (n=6) during oxidative phosphorylation. This was accompanied by greater citrate synthase and lactate dehydrogenase enzyme activity in myostatin-deficient soleus (29% and 80% respectively). Myostatin-deficient gastrocnemius (n=7) showed 26% lower oxygen consumption during uncoupled respiration, and 34% lower oxygen consumption when oxidising glycerol-3-phosphate compared to wild-type gastrocnemius (n=8). Citrate synthase activity was not significantly different and lactate dehydrogenase activity 26% greater in myostatin-deficient gastrocnemius compared to wild-type gastrocnemius.Conclusion: These data suggest that myostatin-deficiency exerts fiber-type specific effects on skeletal muscle mitochondrial function.on skeletal muscle mitochondrial function.)
Chu SRS 2011 + (Aim: To determine the impact of cold ischa … Aim: To determine the impact of cold ischaemia on hepatic mitochondrial function in University of Wisconsin (UW) solution in the setting of hepatic steatosis.Methods: Livers were harvested from 10-week old genetically obese (ob/ob, ''n'' = 9) or lean C57 control mice (''n'' = 9); and preserved in ice-cold UW solution. Mitochondrial function analysis was performed on permeabilised liver samples using a substrate and inhibitor titration protocol in conjunction with a high-resolution respirometer (OROBOROS® Oxygraph-2k) at multiple time-points over 24 h during cold ischemia (CI).Results: Ob/ob mice livers and control mice livers showed either severe (> 60%) or no macrovesicular steatosis respectively. Mitochondria from ob/ob mice livers demonstrated a faster and greater decrease in the percentage of respiration contributing to oxidative phosphorylation over 24 hours of cold storage compared to control mice. After 12 hours of CI, there was also an increased dependence on Complex II respiration relative to Complex I in ob/ob mice livers suggestive of Complex I damage and potential loss of key ATP synthesis efficiency.Conclusion: There was a time-dependant damage of hepatic mitochondrial function during CI. Steatotic livers demonstrated greater mitochondrial dysfunction during CI compared to lean livers.ysfunction during CI compared to lean livers.)
Bakkman 2007 ActaPhysiol + (Aim: To investigate if training during hyp … Aim: To investigate if training during hypoxia (H) improves the adaptation of muscle oxidative function compared with normoxic (N) training performed at the same relative intensity.Method: Eight untrained volunteers performed one-legged cycle training during 4 weeks in a low-pressure chamber. One leg was trained under N conditions and the other leg under hypobaric hypoxia (526 mmHg) at the same relative intensity as during N (65% of maximal power output, ''W''max). Muscle biopsies were taken from vastus lateralis before and after the training period. Muscle samples were analysed for the activities of oxidative enzymes [citrate synthase (CS) and cytochrome c oxidase (COX)] and mitochondrial respiratory function.Results: ''W''max increased with more than 30% over the training period during both N and H. CS activity increased significantly after training during N conditions (+20.8%, P < 0.05) but remained unchanged after H training (+4.5%, ns) with a significant difference between conditions (''P'' < 0.05 H vs. N). COX activity was not significantly changed by training and was not different between exercise conditions [+14.6 (N) vs. -2.3% (H), ns]. Maximal ADP stimulated respiration (state 3) expressed per weight of muscle tended to increase after N (+31.2%, ''P'' < 0.08) but not after H training (+3.2%, ns). No changes were found in state four respiration, respiratory control index, P/O ratio, mitochondrial Ca2+ resistance and apparent ''K''m for oxygen.Conclusion: The training-induced increase in muscle oxidative function observed during N was abolished during H. Altitude training may thus be disadvantageous for adaptation of muscle oxidative function.ng may thus be disadvantageous for adaptation of muscle oxidative function.)
Cour 2014 J Cardiovasc Pharmacol Ther + (Aim: To investigate whether slight variati … Aim: To investigate whether slight variations in core temperature prior to cardiac arrest (CA) influence short-term outcomes and mitochondrial functions.Three groups of New Zealand White rabbits (n = 12/group) were submitted to 15 minutes of CA at 38°C (T-38 group), 39°C (T-39), or 40°C (T 40) and 120 minutes of reperfusion. A Sham-operated group (n = 6) underwent only surgery. Restoration of spontaneous circulation (ROSC), survival, hemodynamics, and pupillary reactivity were recorded. Animals surviving to the end of the observation period were euthanized to assess fresh brain and heart mitochondrial functions (permeability transition and oxidative phosphorylation). Markers of brain and heart damages were also measured.The duration of asphyxia required to induce CA was significantly lower in the T-40 group when compared to the T-38 group (''p''<.05). The rate of ROSC was >80% in all groups (''p''=nonsignificant [ns]). Survival significantly differed among the T-38, T-39, and T-40 groups: 10 (83%) of 12, 7 (58%) of 12, and 4 (33%) of 12, respectively (log-rank test, ''p''=.027). At the end of the protocol, none of the animals in the T-40 group had pupillary reflexes compared to 8 (67%) of 12 in the T-38 group (''p''<.05). Troponin and protein S100B were significantly higher in the T-40 versus T-38 group (''p''<.05). Cardiac arrest significantly impaired both inner mitochondrial membrane integrity and oxidative phosphorylation in all groups. Brain mitochondria disorders were significantly more severe in the T-40 group compared to the T-38 group (''p''< .05).Small changes in body temperature prior to asphyxial CA significantly influence brain mitochondrial functions and short-term outcomes in rabbits.tochondrial functions and short-term outcomes in rabbits.)
Orynbayeva 2015 Nanomedicine (Lond) + (Aim: To successfully translate magneticall … Aim: To successfully translate magnetically mediated cell targeting from bench to bedside, there is a need to systematically assess the potential adverse effects of magnetic nanoparticles (MNPs) interacting with ‘therapeutic’ cells. Here, we examined in detail the effects of internalized polymeric MNPs on primary rat endothelial cells’ structural intactness, metabolic integrity and proliferation potential.Materials & methods: The intactness of cytoskeleton and organelles was studied by fluorescentconfocal microscopy, flow cytometry and high-resolution respirometry. Results: MNPloaded primary endothelial cells preserve intact cytoskeleton and organelles, maintain normal rate of proliferation, calcium signaling and mitochondria energy metabolism.Conclusion: This study provides supportive evidence that MNPs at doses necessaryfor targeting did not induce significant adverse effects on structural integrity and functionality of primary endothelial cells – potential cell therapy vectors.helial cells – potential cell therapy vectors.)
Doerrier 2014 Life Sci + (Aims. Previous data showed that melatonin … Aims. Previous data showed that melatonin maintains liver mitochondrial homeostasis during sepsis, but neither the mechanisms underlying mitochondrial dysfunction nor the target of melatonin are known.Main methods. Here, we analyzed mitochondrial respiration in isolated mouse liver mitochondria with different substrate combinations (glutamate/malate, glutamate/malate/sucinate or succinate/rotenone) to identify mitochondrial defects and melatonin targets during sepsis. Other bioenergetic parameters including a + a3, b, and c + c1 content, mitochondrial mass, and mitochondrial supercomplexes formation were analyzed. Mitochondrial function was assessed during experimental sepsis induced by cecal ligation and puncture (CLP) in livers of 3 mo. C57BL/6 mice at early and late phases of sepsis, i.e., at 8 and 24 h after sepsis induction.Key findings. Septic mice showed mitochondrial injury with a decrease in state 3, respiratory control rate, mitochondrial mass, and cytochrome b and c + c1 content, which was prevented by melatonin treatment. Mitochondrial dysfunction in sepsis was mainly linked to complex I damage, because complex II was far less impaired. These mitochondria preserved the respiratory supramolecular organization, maintaining their electron transport system capacity.Significance. This work strengthens the use of substrate combinations to identify specific respiratory defects and selective melatonin actions in septic mitochondria. Targeting mitochondrial complex I should be a main therapeutical approach in the treatment of sepsis, whereas the use of melatonin should be considered in the therapy of clinical sepsis.sidered in the therapy of clinical sepsis.)
Boushel 2007 Diabetologia + (Aims/hypothesis: Insulin resistance and ty … Aims/hypothesis: Insulin resistance and type 2 diabetes are associated with mitochondrial dysfunction. The aim of the present study was to test the hypothesis that oxidative phosphorylation and electron transport capacity are diminished in the skeletal muscle of type 2 diabetic subjects, as a result of a reduction in the mitochondrial content.Materials and methods: The O2 flux capacity of permeabilised muscle fibres from biopsies of the quadriceps in healthy subjects (''n''=8; age 58±2 years [mean±SEM]; BMI 28±1 kg/m2; fasting plasma glucose 5.4±0.2 mmol/l) and patients with type 2 diabetes (''n''=11; age 62±2 years; BMI 32±2 kg/m2; fasting plasma glucose 9.0±0.8 mmol/l) was measured by high-resolution respirometry.Results: O2 flux expressed per mg of muscle (fresh weight) during ADP-stimulated state 3 respiration was lower ( ''p''<0.05) in patients with type 2 diabetes in the presence of complex I substrate (glutamate) (31±2 vs 43±3 pmol O2 s-1 mg-1) and in response to glutamate + succinate (parallel electron input from complexes I and II) (63±3 vs 85±6 pmol s-1 mg-1). Further increases in O2 flux capacity were observed in response to uncoupling by FCCP, but were again lower ( ''p''<0.05) in type 2 diabetic patients than in healthy control subjects (86±4 vs 109±8 pmol s-1 mg-1). However, when O2 flux was normalised for mitochondrial DNA content or citrate synthase activity,there were no differences in oxidative phosphorylation or electron transport capacity between patients with type 2 diabetes and healthy control subjects.Conclusions/interpretation: Mitochondrial function is normal in type 2 diabetes. Blunting of coupled and uncoupled respiration in type 2 diabetic patients can be attributed to lower mitochondrial content.Conclusions/interpretation: Mitochondrial function is normal in type 2 diabetes. Blunting of coupled and uncoupled respiration in type 2 diabetic patients can be attributed to lower mitochondrial content.)
Winnica 2019 Antioxid Redox Signal + (Aims: Asthma, characterized by airway obst … Aims: Asthma, characterized by airway obstruction and hyper-responsiveness, is more severe and less responsive to treatment in obese subjects. While alterations in mitochondrial function and redox signaling have been implicated in asthma pathogenesis, it is unclear whether these mechanisms differ in lean versus obese asthmatics. In addition, we previously demonstrated that circulating platelets from asthmatic individuals have altered bioenergetics; however, it is unknown whether platelet mitochondrial changes reflect those observed in airway epithelial cells. Herein we hypothesized that lean and obese asthmatics show differential bioenergetics and redox signaling in airway cells and that these alterations could be measured in platelets from the same individual. Results: Using freshly isolated bronchial airway epithelial cells and platelets from lean and obese asthmatics and healthy individuals, we show that both cell types from obese asthmatics have significantly increased glycolysis, basal and maximal respiration, and oxidative stress compared with lean asthmatics and healthy controls. This increased respiration was associated with enhanced arginine metabolism by arginase, which has previously been shown to drive respiration. Inducible nitric oxide synthase (iNOS) was also upregulated in cells from all asthmatics. However, due to nitric oxide synthase uncoupling in obese asthmatics, overall nitric oxide (NO) bioavailability was decreased, preventing NO-dependent inhibition in obese asthmatic cells that was observed in lean asthmatics. Innovation and Conclusion: These data demonstrate bioenergetic differences between lean and obese asthmatics that are, in part, due to differences in NO signaling. They also suggest that the platelet may serve as a useful surrogate to understand redox, oxidative stress and bioenergetic changes in the asthmatic airway.energetic changes in the asthmatic airway.)
Takada 2016 Cardiovasc Res + (Aims: Exercise capacity is reduced in hear … Aims: Exercise capacity is reduced in heart failure (HF) patients, due mostly to skeletal muscle abnormalities including impaired energy metabolism, mitochondrial dysfunction, fibre type transition, and atrophy. Glucagon-like peptide-1 (GLP-1) has been shown to improve exercise capacity in HF patients. We investigated the effects of the administration of a dipeptidyl peptidase (DPP)-4 inhibitor on the exercise capacity and skeletal muscle abnormalities in an HF mouse model after myocardial infarction (MI).Methods and results: MI was created in male C57BL/6J mice by ligating the left coronary artery, and a sham operation was performed in other mice. The mice were then divided into two groups according to the treatment with or without a DPP-4 inhibitor, MK-0626 [1 mg/kg body weight (BW)/day] provided in the diet. Four weeks later, the exercise capacity evaluated by treadmill test was revealed to be limited in the MI mice, and it was ameliorated in the MI + MK-0626 group without affecting the infarct size or cardiac function. The citrate synthase activity, mitochondrial oxidative phosphorylation capacity, supercomplex formation, and their quantity were reduced in the skeletal muscle from the MI mice, and these decreases were normalized in the MI + MK-0626 group, in association with the improvement of mitochondrial biogenesis. Immunohistochemical staining also revealed that a shift toward the fast-twitch fibre type in the MI mice was also reversed by MK-0626. Favourable effects of MK-0626 were significantly inhibited by treatment of GLP-1 antagonist, Exendin-(9-39) (150 pmol/kg BW/min, subcutaneous osmotic pumps) in MI + MK-0626 mice. Similarly, exercise capacity and mitochondrial function were significantly improved by treatment of GLP-1 agonist, Exendin-4 (1 nmol/kg/BW/h, subcutaneous osmotic pumps).Conclusions: A DPP-4 inhibitor may be a novel therapeutic agent against the exercise intolerance seen in HF patients by improving the mitochondrial biogenesis in their skeletal muscle.drial biogenesis in their skeletal muscle.)
Nambu 2021 Cardiovasc Res + (Aims: Exercise intolerance in patients wit … Aims: Exercise intolerance in patients with heart failure (HF) is partly attributed to skeletal muscle abnormalities. We have shown that reactive oxygen species (ROS) play a crucial role in skeletal muscle abnormalities, but the pathogenic mechanism remains unclear. Xanthine oxidase (XO) is reported to be an important mediator of ROS overproduction in ischaemic tissue. Here, we tested the hypothesis that skeletal muscle abnormalities in HF are initially caused by XO-derived ROS and are prevented by the inhibition of their production.Methods and results: Myocardial infarction (MI) was induced in male C57BL/6J mice, which eventually led to HF, and a sham operation was performed in control mice. The time course of XO-derived ROS production in mouse skeletal muscle post-MI was first analysed. XO-derived ROS production was significantly increased in MI mice from Days 1 to 3 post-surgery (acute phase), whereas it did not differ between the MI and sham groups from 7 to 28 days (chronic phase). Second, mice were divided into three groups: sham + vehicle (Sham + Veh), MI + vehicle (MI + Veh), and MI + febuxostat (an XO inhibitor, 5 mg/kg body weight/day; MI + Feb). Febuxostat or vehicle was administered at 1 and 24 h before surgery, and once-daily on Days 1-7 post-surgery. On Day 28 post-surgery, exercise capacity and mitochondrial respiration in skeletal muscle fibres were significantly decreased in MI + Veh compared with Sham + Veh mice. An increase in damaged mitochondria in MI + Veh compared with Sham + Veh mice was also observed. The wet weight and cross-sectional area of slow muscle fibres (higher XO-derived ROS) was reduced via the down-regulation of protein synthesis-associated mTOR-p70S6K signalling in MI + Veh compared with Sham + Veh mice. These impairments were ameliorated in MI + Feb mice, in association with a reduction of XO-derived ROS production, without affecting cardiac function.Conclusion: XO inhibition during the acute phase post-MI can prevent skeletal muscle abnormalities and exercise intolerance in mice with HF. and exercise intolerance in mice with HF.)
Doridot 2014 Antioxid Redox Signal + (Aims: Storkhead Box 1 (STOX1) is a winged- … Aims: Storkhead Box 1 (STOX1) is a winged-helix transcription factor implicated in the genetic forms of a high-prevalence human gestational disease, preeclampsia. STOX1 overexpression confers preeclampsia-like transcriptomic features to trophoblastic cell lines, and preeclampsia symptoms to pregnant mice. The aim of this work was to evaluate the impact of STOX1 on free radical equilibrium and mitochondrial function, ''in vitro'' and ''in vivo''. Results: Transcriptome analysis of STOX1-transgenic versus non-transgenic placentas at 16.5 days of gestation revealed alterations of mitochondria-related pathways. Placentas overexpressing STOX1 displayed altered mitochondrial mass and were severely biased towards protein nitration, indicating nitroso-redox imbalance ''in vivo''. Trophoblast cells overexpressing STOX1 displayed an increased mitochondrial activity at 20% O2 and in hypoxia, despite a reduction of the mitochondrial mass in this situation. STOX1 overexpression is therefore associated to hyperactive mitochondria leading to increased free radical production. Moreover, nitric oxide (NO) production pathways were activated, resulting in peroxynitrite formation. At low oxygen pressure, STOX1 overexpression in the placenta as well as in a trophoblast cell line, switched the free radical balance from Reactive Oxygen Species (ROS) to Reactive Nitrogen Species (RNS). Innovation: In preeclamptic placentas, NO interacts with ROS to generate peroxynitrite and nitrated proteins as end products. This process will deprive the maternal organism of NO, a crucial vasodilator molecule. Conclusion: Our data posit STOX1 as a genetic switch in the ROS/RNS balance and suggest an explanation for elevated blood pressure in preeclampsia.r elevated blood pressure in preeclampsia.)
Hu 2024 Ecotoxicol Environ Saf + (Airborne fine particulate matter (PM<su … Airborne fine particulate matter (PM2.5) exposure is closely associated with metabolic disturbance, in which brown adipose tissue (BAT) is one of the main contributing organs. However, knowledge of the phenotype and mechanism of PM2.5 exposure-impaired BAT is quite limited. In the study, male C57BL/6 mice at three different life phases (young, adult, and middle-aged) were simultaneously exposed to concentrated ambient PM2.5 or filtered air for 8 weeks using a whole-body inhalational exposure system. H&E staining and high-resolution respirometry were used to assess the size of adipocytes and mitochondrial function. Transcriptomics was performed to determine the differentially expressed genes in BAT. Quantitative RT-PCR, immunohistochemistry staining, and immunoblots were performed to verify the transcriptomics and explore the mechanism for BAT mitochondrial dysfunction. Firstly, PM2.5 exposure caused altered BAT morphology and mitochondrial dysfunction in middle-aged but not young or adult mice. Furthermore, PM2.5 exposure increased cellular senescence in BAT of middle-aged mice, accompanied by cell cycle arrest, impaired DNA replication, and inhibited AKT signaling pathway. Moreover, PM2.5 exposure disrupted apoptosis and autophagy homeostasis in BAT of middle-aged mice. Therefore, BAT in middle-aged mice was more vulnerable to PM2.5 exposure, and the cellular senescence-initiated apoptosis, autophagy, and mitochondrial dysfunction may be the mechanism of PM2.5 exposure-induced BAT impairment.ated apoptosis, autophagy, and mitochondrial dysfunction may be the mechanism of PM2.5 exposure-induced BAT impairment.)
Goo 2012 PLoS One + (Akt, a serine/threonine kinase has been sh … Akt, a serine/threonine kinase has been shown to stimulate glycolysis in cancer cells but its role in mitochondrial respiration is unknown. Using PTEN-knockout mouse embryonic fibroblasts (MEF(PTEN-/-)) with hyper-activated Akt as a cell model, we observed a higher respiratory capacity in MEF(PTEN-/-) compared to the wildtype (MEF(WT)). The respiratory phenotype observed in MEF(PTEN-/-) was reproduced in MEF(WT) by gene silencing of PTEN which substantiated its role in regulating mitochondrial function. The increased activities of the respiratory complexes (RCs) I, III and IV were retained in the same relative proportions as those present in MEF(WT), alluding to a possible co-ordinated regulation by PTEN/Akt. Using LY294002 (a PI3K inhibitor) and Akt inhibitor IV, we showed that the regulation of enzyme activities and protein expressions of the RCs was dependent on PI3K/Akt. There was insignificant difference in the protein expressions of mitochondrial transcription factor: peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and its downstream targets, the nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (mtTFA) between MEF(PTEN-/-) and MEF(WT). Similarly, mRNA levels of the same subunits of the RCs detected in Western blots were not significantly different between MEF(PTEN-/-) and MEF(WT) suggesting that the regulation by Akt on mitochondrial function was probably not via gene transcription. On the other hand, a decrease of total 4E-BP1 with a higher expression of its phosphorylated form relative to total 4E-BP1 was found in MEF(PTEN-/-), which inferred that the regulation of mitochondrial respiratory activities by Akt was in part through this protein translation pathway. Notably, gene silencing of 4E-BP1 up-regulated the protein expressions of all RCs and the action of 4E-BP1 appeared to be specific to these mitochondrial proteins. In conclusion, PTEN inactivation bestowed a bioenergetic advantage to the cells by up-regulating mitochondrial respiratory capacity through the 4E-BP1-mediated protein translation pathway.-BP1-mediated protein translation pathway.)
Jasz 2021 J Cell Mol Med + (Albeit previous experiments suggest potent … Albeit previous experiments suggest potential anti-inflammatory effect of exogenous methane (CH4) in various organs, the mechanism of its bioactivity is not entirely understood. We aimed to investigate the potential mitochondrial effects and the underlying mechanisms of CH4 in rat cardiomyocytes and mitochondria under simulated ischaemia/reperfusion (sI/R) conditions. Three-day-old cultured cardiomyocytes were treated with 2.2% CH4 -artificial air mixture during 2-hour-long reoxygenation following 4-hour-long anoxia (sI/R and sI/R + CH4 , n = 6-6), with normoxic groups serving as controls (SH and SH + CH4 ; n = 6-6). Mitochondrial functions were investigated with high-resolution respirometry, and mitochondrial membrane injury was detected by cytochrome c release and apoptotic characteristics by using TUNEL staining. CH4 admixture had no effect on complex II (CII)-linked respiration under normoxia but significantly decreased the complex I (CI)-linked oxygen consumption. Nevertheless, addition of CH4 in the sI/R + CH4 group significantly reduced the respiratory activity of CII in contrast to CI and the CH4 treatment diminished mitochondrial H2O2 production. Substrate-induced changes to membrane potential were partially preserved by CH4 , and additionally, cytochrome c release and apoptosis of cardiomyocytes were reduced in the CH4 -treated group. In conclusion, the addition of CH4 decreases mitochondrial ROS generation via blockade of electron transport at CI and reduces anoxia-reoxygenation-induced mitochondrial dysfunction and cardiomyocyte injury ''in vitro''.4 decreases mitochondrial ROS generation via blockade of electron transport at CI and reduces anoxia-reoxygenation-induced mitochondrial dysfunction and cardiomyocyte injury ''in vitro''.)
Karadayian 2015 Neuroscience + (Alcohol hangover (AH) is defined as the te … Alcohol hangover (AH) is defined as the temporary state after alcohol binge-like drinking, starting when ethanol (EtOH) is absent in plasma. Previous data indicate that AH induces mitochondrial dysfunction and free radical production in mouse brain cortex. The aim of this work was to study mitochondrial function and reactive oxygen species production in mouse cerebellum at the onset of AH. Male mice received a single i.p. injection of EtOH (3.8g/kg BW) or saline solution. Mitochondrial function was evaluated 6h after injection (AH onset). At the onset of AH, malate-glutamate and succinate-supported state 4 oxygen uptake was 2.3 and 1.9-fold increased leading to a reduction in respiratory control of 55% and 48% respectively, as compared with controls. Decreases of 38% and 16% were found in Complex I-III and IV activities. Complex II-III activity was not affected by AH. Mitochondrial membrane potential and mitochondrial permeability changes were evaluated by flow cytometry. Mitochondrial membrane potential and permeability were decreased by AH in cerebellum mitochondria. Together with this, AH induced a 25% increase in superoxide anion and a 92% increase in hydrogen peroxide production in cerebellum mitochondria. Related to nitric oxide (NO) metabolism, neuronal nitric oxide synthase (nNOS) protein expression was 52% decreased by the hangover condition compared with control group. No differences were found in cerebellum NO production between control and treated mice. The present work demonstrates that the physiopathological state of AH involves mitochondrial dysfunction in mouse cerebellum showing the long-lasting effects of acute EtOH exposure in the central nervous system.OH exposure in the central nervous system.)
Wang 2009 Int J Clin Exp Pathol + (Alcohol use has become far too prevalent i … Alcohol use has become far too prevalent in our society. Alcohol kills 6.5 times more youth than all other illicit drugs combined. In combination with traumatic and hemorrhagic injuries, alcohol results in a much higher mortality rate. Alcohol, alone and in high dosages, also causes great damage to the body, often leading to death as well. Thus, it is of utmost importance that research is conducted to help explain the pathological mechanism of high fatalities and injuries associated with alcohol use. In order to simulate this complex situation in vitro, a rat hepatoma cell line (H-II-4-E) was exposed to various concentrations of ethanol as well as the condition of hypoxia. Hypoxia mimics the primary level of tissue damage caused by hemorrhage after impact in a car accident. In this way, we tested the hypothesis that the presence of ethanol in combination with hypoxia causes greater cellular damage compared to conditions of ethanol or hypoxia alone. Ethanol, alone and in high concentrations, was found to greatly affect cell function as shown by decreased cellular ATP levels, increased LDH release, and a downregulated expression of CYP2E1 gene. By adding the condition of hypoxia to low concentrations of ethanol, cellular damage increased dramatically as well. Decreased gene expression and protein levels of CYP2E1 correlated with increased hepatocyte injury and thus, this enzyme may significantly contribute to the severity of cellular damage. These results provide useful information for future research on the effects of ethanol in combination with hemorrhage on cells in vitro, simulating the condition of driving while intoxicated and binge drinking.ving while intoxicated and binge drinking.)
Wen 2023 PLoS One + (Alcoholic myopathy is caused by chronic co … Alcoholic myopathy is caused by chronic consumption of alcohol (ethanol) and is characterized by weakness and atrophy of skeletal muscle. Regular exercise is one of the important ways to prevent or alleviate skeletal muscle myopathy. However, the beneficial effects and the exact mechanisms underlying regular exercise on alcohol myopathy remain unclear. In this study, a model of alcoholic myopathy was established using zebrafish soaked in 0.5% ethanol. Additionally, these zebrafish were intervened to swim for 8 weeks at an exercise intensity of 30% of the absolute critical swimming speed (Ucrit), aiming to explore the beneficial effects and underlying mechanisms of regular exercise on alcoholic myopathy. This study found that regular exercise inhibited protein degradation, improved locomotion ability, and increased muscle fiber cross-sectional area (CSA) in ethanol-treated zebrafish. In addition, regular exercise increases the functional activity of mitochondrial respiratory chain (MRC) complexes and upregulates the expression levels of MRC complexes. Regular exercise can also improve oxidative stress and mitochondrial dynamics in zebrafish skeletal muscle induced by ethanol. Additionally, regular exercise can activate mitochondrial biogenesis and inhibit mitochondrial unfolded protein response (UPRmt). Together, our results suggest regular exercise is an effective intervention strategy to improve mitochondrial homeostasis to attenuate alcoholic myopathy.meostasis to attenuate alcoholic myopathy.)

ALGAEUROPE 2018 Amsterdam NL + (AlgaEurope 2018, Amsterdam, Netherlands, 2018)

AlgaEurope 2020 Virtual Event + (AlgaEurope 2020, Virtual Event, 2020, NextGen-O2k)
AlgaEurope 2022 Rome IT + (AlgaEurope 2022, Rome, IT, 2022)
Gnaiger 2022 Abstract Bioblast-PB + (Algal biotechnology has emerged as a high- … Algal biotechnology has emerged as a high-potential industry for efficient and CO2-neutral production of biomass providing biofuels, food and feed, and a variety of carbon-based chemicals and pharmaceuticals. Algal metabolism is directly involved in the regulation of growth, cell concentration, and biosynthesis of biotechnologically-relevant phytochemicals such as vitamins, antioxidants, and immune response boosters. Photoautotrophic growth rates of algae are based on light-to-chemical energy conversion and CO2 fixation, and any optimization of biomass production requires maximizing energy-use efficiency of photosynthesis and respiration, both of which vary as a function of light intensity. As such, the bioenergetic crosstalk between mitochondria and chloroplasts plays a key role in maintaining metabolic integrity and controlling intermediary metabolite production. In the present study, we investigated how photosynthetic O2 production and respiratory O2 consumption was influenced as a function of light intensity, O2 concentration, and culture density in the unicellular model green alga ''Chlamydomonas reinhardtii''. Cultures were grown photoautotrophically in a modified Tris-Phosphate growth medium (TRIS, N- and P-nutrient replete) at 25 °C, pH 7.0, and light intensity of 100 µmol photons·s-1·m-2 (16:8 h light:dark cycle). Kinetics of light-induced O2 production and dark respiration of these microalgae was measured under culture conditions and three cell concentrations, while varying O2 concentrations in the Oroboros [[NextGen-O2k]] equipped with the PhotoBiology-Module [1] during stepwise increases of blue actinic light from from 10 to 350 µmol∙s-1∙m-2, followed by darkness, again at various controlled O2 concentrations. Maximum net photosynthesis was inhibited by 40 % at hyperoxic O2 concentrations of 550 to 650 µM, when ROS production is known to be increased [2,3]. Transient light-enhanced dark respiration [4] peaked within 30 to 60 s after light-dark transitions and was 3.5- to 4-fold higher than steady-state dark respiration independent of O2 concentration in the range of 200 to 650 µM. We conclude that high-resolution photorespiratory analysis provides a new method to investigate the oxygen kinetics of O2 production and O2 consumption that reveal interactions of chloroplasts and mitochondria under precisely regulated experimental light and oxygen regimes.# Went N, Di Marcello M, Gnaiger E (2021) Oxygen dependence of photosynthesis and light-enhanced dark respiration studied by High-Resolution PhotoRespirometry. https://doi.org/10.26124/mitofit:2021-0005# Komlódi T, Sobotka O, Gnaiger E (2021) Facts and artefacts on the oxygen dependence of hydrogen peroxide production using Amplex UltraRed. https://doi.org/10.26124/bec:2021-0004# Shimakawa G, Kohara A, Miyake C (2020) Characterization of light-enhanced respiration in cyanobacteria. https://doi.org/10.3390/ijms22010342drogen peroxide production using Amplex UltraRed. https://doi.org/10.26124/bec:2021-0004 # Shimakawa G, Kohara A, Miyake C (2020) Characterization of light-enhanced respiration in cyanobacteria. https://doi.org/10.3390/ijms22010342 )
Gerisch 2020 Dev Cell + (All animals have evolved the ability to su … All animals have evolved the ability to survive nutrient deprivation, and nutrient signaling pathways are conserved modulators of health and disease. In ''C. elegans'', late-larval starvation provokes the adult reproductive diapause (ARD), a long-lived quiescent state that enables survival for months without food, yet underlying molecular mechanisms remain unknown. Here, we show that ARD is distinct from other forms of diapause, showing little requirement for canonical longevity pathways, autophagy, and fat metabolism. Instead it requires the HLH-30/TFEB transcription factor to promote the morphological and physiological remodeling involved in ARD entry, survival, and recovery, suggesting that HLH-30 is a master regulator of reproductive quiescence. HLH-30 transcriptome and genetic analyses reveal that Max-like HLH factors, AMP-kinase, mTOR, protein synthesis, and mitochondrial fusion are target processes that promote ARD longevity. ARD thus rewires metabolism to ensure long-term survival and may illuminate similar mechanisms acting in stem cell quiescence and long-term fasting.Copyright © 2020 Elsevier Inc. All rights reserved. 2020 Elsevier Inc. All rights reserved.)
Hernansanz-Agustin 2019 bioRxiv + (All metazoans depend on O2</ … All metazoans depend on O2 delivery and consumption by the mitochondrial oxidative phosphorylation (OXPHOS) system to produce energy. A decrease in O2 availability (hypoxia) leads to profound metabolic rewiring. In addition, OXPHOS uses O2 to produce reactive oxygen species (ROS) that can drive cell adaptations through redox signalling, but also trigger cell damage, and both phenomena occur in hypoxia. However, the precise mechanism by which acute hypoxia triggers mitochondrial ROS production is still unknown. Ca2+ is one of the best known examples of an ion acting as a second messenger, yet the role ascribed to Na+ is to serve as a mere mediator of membrane potential and collaborating in ion transport. Here we show that Na+ acts as a second messenger regulating OXPHOS function and ROS production by modulating fluidity of the inner mitochondrial membrane (IMM). We found that a conformational shift in mitochondrial complex I during acute hypoxia drives the acidification of the matrix and solubilization of calcium phosphate precipitates. The concomitant increase in matrix free-Ca2+ activates the mitochondrial Na+/Ca2+ exchanger (NCLX), which imports Na+ into the matrix. Na+ interacts with phospholipids reducing IMM fluidity and mobility of free ubiquinone between complex II and complex III, but not inside supercomplexes. As a consequence, superoxide is produced at complex III, generating a redox signal. Inhibition of mitochondrial Na+ import through NCLX is sufficient to block this pathway, preventing adaptation to hypoxia. These results reveal that Na+ import into the mitochondrial matrix controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences in cellular metabolismlt;/sup> import into the mitochondrial matrix controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences in cellular metabolism)
Hernansanz-Agustin 2020 Nature + (All metazoans depend on the consumption of … All metazoans depend on the consumption of O2 by the mitochondrial oxidative phosphorylation system (OXPHOS) to produce energy. In addition, the OXPHOS uses O2 to produce reactive oxygen species that can drive cell adaptations, a phenomenon that occurs in hypoxia and whose precise mechanism remains unknown. Ca2+ is the best known ion that acts as a second messenger, yet the role ascribed to Na+ is to serve as a mere mediator of membrane potential. Here we show that Na+ acts as a second messenger that regulates OXPHOS function and the production of reactive oxygen species by modulating the fluidity of the inner mitochondrial membrane. A conformational shift in mitochondrial complex I during acute hypoxia drives acidification of the matrix and the release of free Ca2+ from calcium phosphate (CaP) precipitates. The concomitant activation of the mitochondrial Na+/Ca2+ exchanger promotes the import of Na+ into the matrix. Na+ interacts with phospholipids, reducing inner mitochondrial membrane fluidity and the mobility of free ubiquinone between complex II and complex III, but not inside supercomplexes. As a consequence, superoxide is produced at complex III. The inhibition of Na+ import through the Na+/Ca2+ exchanger is sufficient to block this pathway, preventing adaptation to hypoxia. These results reveal that Na+ controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences for cellular metabolism.oxia. These results reveal that Na+ controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences for cellular metabolism.)
Neves 2015 Elife + (All organisms live within a given thermal … All organisms live within a given thermal range, but little is known about the mechanisms setting the limits of this range. We uncovered cellular features exhibiting signature changes at thermal limits in ''Caenorhabditis elegans'' embryos. These included changes in embryo size and shape, which were also observed in ''Caenorhabditis briggsae'', indicating evolutionary conservation. We hypothesized that such changes could reflect restricted aerobic capacity at thermal limits. Accordingly, we uncovered that relative respiration in ''C. elegans'' embryos decreases at the thermal limits as compared to within the thermal range. Furthermore, by compromising components of the respiratory chain, we demonstrated that the reliance on aerobic metabolism is reduced at thermal limits. Moreover, embryos thus compromised exhibited signature changes in size and shape already within the thermal range. We conclude that restricted aerobic metabolism at the thermal limits contributes to setting the thermal range in a metazoan organism. the thermal range in a metazoan organism.)
Wilmshurst 1998 BMJ + (All organisms require oxygen for metabolis … All organisms require oxygen for metabolism, but the oxygen in water is unavailable to mammals. Divers (and diving mammals such as whales and seals) are entirely dependent on the oxygen carried in the air in their lungs or their gas supply. Divers also have a paradoxical problem with oxygen. At higher partial pressures oxygen causes acute toxicity leading to convulsions. To understand the diver's narrow knife edge between fatal hypoxia and fatal hyperoxia we need to recall some of the physical properties of gases. At sea level atmospheric pressure is 1 bar absolute (1 standard atmosphere =101 kPa=1.013 bars). The weight of the atmosphere exerts a pressure which will support a column of water 10 m high; 10 m under water the pressure on a diver is 200 kPa. The volume of gas in an early diving bell full of air at sea level is halved at 10 m according to Boyle's law; at 20 m pressure is 300 kPa absolute and the gas is compressed into one third the volume. Dry air is composed of roughly 21 % oxygen, 78 % nitrogen, and 1 % other gases. According to Dalton's law the partial pressure of oxygen at any depth will be 21 % of the total pressure exerted by the air and the partial pressure of nitrogen will be 78 % of total pressure. Gases dissolve in the liquid with which they are in contact. Nitrogen is fat soluble and at sea level we have several litres dissolved in our bodies. If the partial pressure of nitrogen is doubled (by breathing air at 10 m depth) for long enough for equilibration to take place we will contain twice as many dissolved nitrogen molecules as at sea level. Gases dissolve in the liquid with which they are in contact. Nitrogen is fat soluble and at sea level we have several litres dissolved in our bodies. If the partial pressure of nitrogen is doubled (by breathing air at 10 m depth) for long enough for equilibration to take place we will contain twice as many dissolved nitrogen molecules as at sea level. The effect of the increased partial pressures of oxygen is more complex. Doubling our inspired partial pressure of oxygen doubles the amount of oxygen in solution but does not double the amount of oxygen in the body since a large part of our oxygen content is bound to oxygen carrying pigments. The haemoglobin in arterial blood is virtually saturated at an inspired partial pressure of oxygen (Fio2) of 21 kPa, and increasing the partial pressure of oxygen has little effect on the amount of oxygen bound to haemoglobin.the amount of oxygen bound to haemoglobin.)
Silvia 1976 American Psychological Association + (All students and professors need to write, … All students and professors need to write, and many struggle to finish their stalled dissertations, journal articles, book chapters, or grant proposals. Writing is hard work and can be difficult to wedge into a frenetic academic schedule.In this practical, light-hearted, and encouraging book, Paul Silvia explains that writing productively does not require innate skills or special traits but specific tactics and actions. Drawing examples from his own field of psychology, he shows readers how to overcome motivational roadblocks and become prolific without sacrificing evenings, weekends, and vacations. After describing strategies for writing productively, the author gives detailed advice from the trenches on how to write, submit, revise, and resubmit articles, how to improve writing quality, and how to write and publish academic work.nd how to write and publish academic work.)
Cubizolle 2020 J Cell Mol Med + (All-trans-retinal (atRAL) is a highly reac … All-trans-retinal (atRAL) is a highly reactive carbonyl specie, known for its reactivity on cellular phosphatidylethanolamine in photoreceptor. It is generated by photoisomerization of 11-cis-retinal chromophore linked to opsin by the Schiff's base reaction. In ABCA4-associated autosomal recessive Stargardt macular dystrophy, atRAL results in carbonyl and oxidative stress, which leads to bisretinoid A2E, accumulation in the retinal pigment epithelium (RPE). This A2E-accumulation presents as lipofuscin fluorescent pigment, and its photooxidation causes subsequent damage. Here we describe protection against a lethal dose of atRAL in both photoreceptors and RPE in primary cultures by a lipidic polyphenol derivative, an isopropyl-phloroglucinol linked to DHA, referred to as IP-DHA. Next, we addressed the cellular and molecular defence mechanisms in commonly used human ARPE-19 cells. We determined that both polyunsaturated fatty acid and isopropyl substituents bond to phloroglucinol are essential to confer the highest protection. IP-DHA responds rapidly against the toxicity of atRAL and its protective effect persists. This healthy effect of IP-DHA applies to the mitochondrial respiration. IP-DHA also rescues RPE cells subjected to the toxic effects of A2E after blue light exposure. Together, our findings suggest that the beneficial role of IP-DHA in retinal cells involves both anti-carbonyl and anti-oxidative capacities.© 2020 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.ndation for Cellular and Molecular Medicine.)
Qi 2017 Ann Allergy Asthma Immunol + (Allergic rhinitis is the most common of th … Allergic rhinitis is the most common of the atopic diseases, affecting up to 25% of the population worldwide. Grass pollen sensitization has been recognized as a major cause of allergic rhinitis. On the pathophysiologic level, allergic rhinitis is an IgE-mediated inflammation of the nasal mucosa. Grass pollen allergy, commonly called hay fever, can also cause more general symptoms, such as fatigue and unwellness as seen in flulike syndromes. This might be partly related to the activation of a systemic inflammatory pathway after the local nasal inflammatory response, but data from studies concerning the systemic effects of nasal mucosal allergen exposure are limited....ucosal allergen exposure are limited. ...)
Mutschler 2013 + (Allergien, Burn-out, Fibromyalgie, Multipl … Allergien, Burn-out, Fibromyalgie, Multiple Chemikalien-Sensitivität, Fatigue-Syndrom, … die Liste der Krankheiten, die die herkömmliche Medizin – vor allem für Kassenpatienten – weder gut diagnostizieren noch wirklich erfolgreich behandeln kann, ist lang. Hinzu kommt, dass zu den bereits Genannten fast unbegrenzt weitere Erkrankungen hinzugefügt werden müssen, von denen die Lehrmedizin meint, dass sie sie behandeln kann, ihre Behandlung dem Patienten jedoch oft auch erheblich schadet: Herz-Kreislauf-Erkrankungen, Krebs, Autoimmunerkrankungen, neurodegenerative Erkrankungen, Depressionen und viele mehr. Diese Patienten werden mit einer Reihe von Pharmaka versorgt, die die Symptome der Erkrankung abmildert oder bestenfalls zum Verschwinden bringt, jedoch wird dieser „Erfolg“ mit erheblichen Nebenwirkungen teuer erkauft. Meist ist die jahrzehntelange „Patienten-Karriere“ bereits klar vorgezeichnet, wenn ein Mensch in die Mühle der pharmazeutisch geprägten Medizin gerät. Es ist nur eine Frage der Zeit, wann die nächsten schwerwiegenden Symptome auftreten. Denn viele der millionenfach verschriebenen Arzneien greifen in die Physiologie einer jeden Körperzelle ein und können Stoffwechselwege ausbremsen oder gar Schäden an Organellen erzeugen – allem voran Schäden an den Mitochondrien (sekundäre Mitochondriopathien), den existenziellen Zellbestandteilen für die Energieversorgung in der kleinesten Einheit eines jeden Organs und Gewebes. Ganz zu schweigen davon, dass die ursächlich auslösenden physiologischen Bedingungen weder erkannt noch behoben werden, damit unterschwellig fortbestehen und langfristig folgerichtig weitere, neue Symptome und Erkrankungen zum Vorschein bringen. Wie viel besser steht bei einem Vergleich doch die mitochondriale Medizin mit einer klar definierten Ausrichtung auf die Unterstützung und Förderung der Zellphysiologie da! Sie setzt darauf,die tatsächlichen Belastungen des Körpers und seiner Zellen aufzuspüren und weitestmöglich zu beseitigen,Mängel im Stoffwechsel zu orten und durch eine für den Patienten passende Ernährung und die gezielte Gabe von Makro- und Mikroelementensowie weiteren Vitalstoffen aufzuheben sowie durch geeignete Maßnahmen die Regeneration und die Teilung der Mitochondrien anzuregen und den gesamten Zellstoffwechsel zu unterstützen und zu fördern.So kann mit der Zeit wieder Gesundheit entstehen und tatsächliche Heilung ist möglich.ehen und tatsächliche Heilung ist möglich.)
Kovalev 2018 EMBS + (Allometric decline of mass-specific metabo … Allometric decline of mass-specific metabolic rate with increasing body size in organisms is a long-known and well-documented phenomenon. The patterns observed at the organismal level indicate fundamental allometric changes in the rate of cellular metabolism and mitochondrial functioning; however, the mechanistic causes of these differences remain under debate. The aerobic metabolic rate is performed through the mitochondrial pathway of oxidative phosphorylation. Therefore, it is meaningful to predict that allometric pattern for mitochondrial functioning would reflect the pattern of aerobic metabolism. Surprisingly, there have been relatively few studies that have assessed the possible link between mitochondrial respiration and body size in invertebrates. We studied body size dependence of mitochondrial respiration of blue mussels ''Mytilus edulis'' L. Mussels were of the same age (3 years), but differed in size. In order to test functional capacities of mitochondria from mussels of different sizes respiration was determined at normal (15°C) and elevated (27°C) exposure temperatures. Mitochondria were isolated from hepatopancreas and respiration rate was measured using high-resolution respirometry method (by Oxygraph-2k, Oroboros Instruments). Substrates, inhibitors and uncoupling agents for oxidative phosphorylation (OXPHOS) and electron transport system (ETS) were added step-by-step in order to assess maximal respiration rates, respiratory control ratio, proton leak, activity and impact of all complexes of ETC. Temperature significantly accelerated state 3 (ADP-stimulated) mitochondrial respiration, maximal respiration with uncoupled ETS, and caused an increase of Respiratory Control Ratios. On the contrary, state 4 respiration (indicative of the proton leak) as well as respiration related to electron flux through complexes of ETC did not show an increase at stress temperature (27°C). Body size of mussels had a strong effect on most studied parameters. ADP-stimulated respiration, electron flux through complex IV, proton leak and uncoupled respiration showed a pronounced increase with body mass of mussels with power coefficients of 1.8, 1.2, 0.2 and 0.8, respectively. The obtained results showed that larger mussels had higher OXPHOS rates than smaller ones. Since all mussels were of the same age, larger ones obviously were characterized by rapid growth. It is possible that elevated growth abilities in some specimens compared to the others result from more efficient metabolic regulation which in turn is related to higher mitochondrial capacities.elated to higher mitochondrial capacities.)
Miettinen 2017 Trends Cell Biol + (Allometric scaling of metabolic rate resul … Allometric scaling of metabolic rate results in lower total mitochondrial oxygen consumption with increasing organismal size. This is considered a universal law in biology. Here, we discuss how allometric laws impose size-dependent limits to mitochondrial activity at the cellular level. This cell-size-dependent mitochondrial metabolic activity results in nonlinear scaling of metabolism in proliferating cells, which can explain size homeostasis. The allometry in mitochondrial activity can be controlled through mitochondrial fusion and fission machinery, suggesting that mitochondrial connectivity can bypass transport limitations, the presumed biophysical basis for allometry. As physical size affects cellular functionality, cell-size-dependent metabolism becomes directly relevant for development, metabolic diseases, and aging.evelopment, metabolic diseases, and aging.)
Nold 2019 Psychoneuroendocrinology + (Allostasis is the process by which the bod … Allostasis is the process by which the body’s physiological systems adapt to environmental changes. Chronic stress increases the allostatic load to the body, producing wear and tear that could, over time, become pathological. In this study, young adult male Wistar Kyoto rats were exposed to an unpredictable chronic mild stress (uCMS) protocol to increase allostatic load. First, physiological systems which may be affected by extended uCMS exposure were assessed. Secondly, 5 weeks of uCMS were used to investigate early adaptations in the previously selected systems. Adverse experiences during developmentally sensitive periods like adolescence are known to severely alter the individual stress vulnerability with long-lasting effects. To elucidate how early life adversity impacts stress reactivity in adulthood, an additional group with juvenile single-housing (JSH) prior to uCMS was included in the second cohort. The aim of this work was to assess the impact of chronic stress with or without adversity during adolescence on two domains known to be impacted in numerous stress-related disorders: mitochondrial energy metabolism and the immune system. Both, uCMS and adolescence stress increased kynurenine and kynurenic acid in plasma, suggesting a protective, anti-oxidant response from the kynurenine pathway. Furthermore, uCMS resulted in a down-regulation of immediate early gene expression in the prefrontal cortex and hippocampus, while only rats with the double-hit of adolescent stress and uCMS demonstrated increased mitochondrial activity in the hippocampus. These results suggest that early life adversity may impact on allostatic load by increasing energetic requirements in the brain.asing energetic requirements in the brain.)
Opperdoes 2024 BMC Genomics + (Almost all extant organisms use the same, … Almost all extant organisms use the same, so-called canonical, genetic code with departures from it being very rare. Even more exceptional are the instances when a eukaryote with non-canonical code can be easily cultivated and has its whole genome and transcriptome sequenced. This is the case of ''Blastocrithidia nonstop'', a trypanosomatid flagellate that reassigned all three stop codons to encode amino acids.We ''in silico'' predicted the metabolism of ''B. nonstop'' and compared it with that of the well-studied human parasites ''Trypanosoma brucei'' and ''Leishmania major''. The mapped mitochondrial, glycosomal and cytosolic metabolism contains all typical features of these diverse and important parasites. We also provided experimental validation for some of the predicted observations, concerning, specifically presence of glycosomes, cellular respiration, and assembly of the respiratory complexes.In an unusual comparison of metabolism between a parasitic protist with a massively altered genetic code and its close relatives that rely on a canonical code we showed that the dramatic differences on the level of nucleic acids do not seem to be reflected in the metabolisms. Moreover, although the genome of ''B. nonstop'' is extremely AT-rich, we could not find any alterations of its pyrimidine synthesis pathway when compared to other trypanosomatids. Hence, we conclude that the dramatic alteration of the genetic code of ''B. nonstop'' has no significant repercussions on the metabolism of this flagellate.ions on the metabolism of this flagellate.)
Zhu 2019 Aging Cell + (Alogliptin is a commonly prescribed drug t … Alogliptin is a commonly prescribed drug treating patients with type 2 diabetes. Here, we show that long-term intervention with alogliptin (0.03% w/w in diet) improves survival and health of mice on a high-fat diet. Alogliptin intervention takes beneficial effects associated with longevity, including increased insulin sensitivity, attenuated functionality decline, decreased organ pathology, preserved mitochondrial function, and reduced oxidative stress. Autophagy activation is proposed as an underlying mechanism of these beneficial effects. We conclude that alogliptin intervention could be considered as a potential strategy for extending lifespan and healthspan in obesity and overweight.© 2019 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.mical Society and John Wiley & Sons Ltd.)
Dieter 2022 Int J Mol Sci + (Alpha lipoic acid (ALA) is a sulphur-conta … Alpha lipoic acid (ALA) is a sulphur-containing organic compound, derived from octanoic acid, and an important cofactor for mitochondrial respiratory enzymes. It has strong antioxidant properties that improve mitochondrial function. We investigated if ALA improves mitochondrial dysfunction in a cellular model of Alzheimer's disease (AD).SH-SY5Y-APP695 cells were used as a model for an early stage of AD. Vector-transfected SH-SY5Y-MOCK cells served as controls. Using these cells, we investigated mitochondrial respiration (OXPHOS), mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) production, and citrate synthase activity (CS) in cells treated with ALA. Cells were treated for 24 h with different concentrations of ALA and with or without the complex I inhibitor rotenone.Incubation with ALA showed a significant increase in ATP levels in both SH-SY5Y-APP695 and SH-SY5Y-MOCK cells. MMP levels were elevated in SH-SY5Y-MOCK cells, treatment with rotenone showed a reduction in MMP, which could be partly alleviated after incubation with ALA in SH-SY5Y-MOCK cells. ALA treatment showed significant differences in respiration chain complex activities in SH-SY5Y-MOCK cells. Citrate synthase activity was unaffected. ROS levels were significantly lower in both cell lines treated with ALA.ALA increased the activity of the different complexes of the respiratory chain, and consequently enhanced the MMP, leading to increased ATP levels indicating improved mitochondrial function. ALA only marginally protects from additional rotenone-induced mitochondrial stress.ly protects from additional rotenone-induced mitochondrial stress.)
Tretter 2005 Philos Trans R Soc Lond B Biol Sci + (Alpha-ketoglutarate dehydrogenase (alpha-K … Alpha-ketoglutarate dehydrogenase (alpha-KGDH) is a highly regulated enzyme, which could determine the metabolic flux through the Krebs cycle. It catalyses the conversion of alpha-ketoglutarate to succinyl-CoA and produces NADH directly providing electrons for the respiratory chain. alpha-KGDH is sensitive to reactive oxygen species (ROS) and inhibition of this enzyme could be critical in the metabolic deficiency induced by oxidative stress. Aconitase in the Krebs cycle is more vulnerable than alpha-KGDH to ROS but as long as alpha-KGDH is functional NADH generation in the Krebs cycle is maintained. NADH supply to the respiratory chain is limited only when alpha-KGDH is also inhibited by ROS. In addition being a key target, alpha-KGDH is able to generate ROS during its catalytic function, which is regulated by the NADH/NAD+ ratio. The pathological relevance of these two features of alpha-KGDH is discussed in this review, particularly in relation to neurodegeneration, as an impaired function of this enzyme has been found to be characteristic for several neurodegenerative diseases.ic for several neurodegenerative diseases.)
Dohlmann 2013 Abstract IOC75 + (Alteration in mitochondrial respiratory ca … Alteration in mitochondrial respiratory capacity has been linked to several conditions that are associated with a sedentary lifestyle, such as obesity and insulin resistance. It is well known that endurance training can diminish these conditions, but some high intensity interval training (HIIT) protocols have shown similar improvements in insulin sensitivity, in spite of the reduced training volume. However it is sparse with literature regarding HIIT and the effect on mitochondrial respiratory capacity. The aim of this study was to investigate the effects of a low volume HIIT protocol on mitochondrial respiratory capacity and VO2max in sedentary overweight adults. 8 healthy sedentary men (n=2) and women (n=6) (age 40±3 yrs, BMI 32±2, VO2max 2383 ±115 ml•min-1) were recruited for this study. They underwent 6 weeks of supervised HIIT on a cycle ergometer (18 sessions of 7x1min exercise bouts interspersed with 1min rest periods). Muscle biopsies were taken from m. vastus lateralis before and after training. Mitochondrial respiratory capacity was measured ex vivo in permeabilized muscle fibers using high resolution respirometry (Oxygraph-2k, Oroboros, Innsbruck, Austria). The respiratory protocol investigated maximal coupled state 3 respiration (complex I + II linked substrates) with the following substrates (malate, glutamate, octanoyl carnitine, succinate and ADP; GMSO3), as well as state 4o (oligomycin; LEAK). Body composition was measured by DXA, and VO2max using an incremental cycle test to exhaustion. Mitochondrial respiratory capacity increased significantly following training; GMSO3 respiration increased by 13% (57± 4 to 64±5 pmol O2•mg-1•s-1) and LEAK respiration increased by 24% (21±2 to 25±2 pmol O2 •mg-1•s-1).The present training protocol didn’t elicit a significant improvement in VO2max (4%, P = 0.37), but time to fatigue during the VO2max test was significantly increased by 18% post training (P <0.001). BMI and body composition were not changed following training.Interestingly the present training protocol induced a significant improvement in mitochondrial respiratory capacity, but not in whole body VO2max, thus implying that the training stimulus was adequate to improve the respiratory capacity locally. The observed improvement in mitochondrial respiratory capacity and time to fatigue suggest that the HIIT training may induce positive metabolic effects that can attenuate the development of lifestyle diseases, independently of VO2max.The project is funded by the EU FP7 program The project is funded by the EU FP7 program)
Rigoni 2016 Abstract Mito Xmas Meeting Innsbruck + (Alteration of mitochondrial ultrastructure … Alteration of mitochondrial ultrastructure has emerged as phenotypical marker of dysfunction. In particular, changes in cristae shape and number regulate the respiratory efficiency of the cell and the release of proapoptotic factors. Moreover, in the last years a growing number of studies have observed a loss of mtDNA associated to mitochondrial related disorders but whether and how mtDNA and nucleoids regulation is influenced by mitochondrial ultrastructure is unknown. To address this question we studied nucleoids distribution and mtDNA copynumber in cellular models where the mitochondrial ultrastructure has been altered. We show that nucleoids distribution vary depending on mitochondrial ultrastructure and accordingly also mtDNA copy number. Furthermore, we have identified a mitochondrial complex that decrease with nucleoids suggesting a relevant role of this complex for nucleoids and mtDNA stability. Our results suggest that nucleoids and mtDNA stability is regulated by mitochondrial ultrastructure.regulated by mitochondrial ultrastructure.)
Schneeberger 2015 Cell Rep + (Alterations in ER homeostasis have been im … Alterations in ER homeostasis have been implicated in the pathophysiology of obesity and type-2 diabetes (T2D). Acute ER stress induction in the hypothalamus produces glucose metabolism perturbations. However, the neurobiological basis linking hypothalamic ER stress with abnormal glucose metabolism remains unknown. Here, we report that genetic and induced models of hypothalamic ER stress are associated with alterations in systemic glucose homeostasis due to increased gluconeogenesis (GNG) independent of body weight changes. Defective alpha melanocyte-stimulating hormone (α-MSH) production underlies this metabolic phenotype, as pharmacological strategies aimed at rescuing hypothalamic α-MSH content reversed this phenotype at metabolic and molecular level. Collectively, our results posit defective α-MSH processing as a fundamental mediator of enhanced GNG in the context of hypothalamic ER stress and establish α-MSH deficiency in proopiomelanocortin (POMC) neurons as a potential contributor to the pathophysiology of T2D.contributor to the pathophysiology of T2D.)
Beaudoin 2014 J Physiol + (Alterations in lipid metabolism within the … Alterations in lipid metabolism within the heart may have a causal role in the establishment of diabetic cardiomyopathy, however this remains equivocal. Therefore, in the current study we determined cardiac mitochondrial bioenergetics in ZDF rats before overt type 2 diabetes and diabetic cardiomyopathy developed. In addition, we utilized resveratrol, a compound previously shown to improve prevent or reverse cardiac dysfunction in high fat-fed rodents, as a tool to potential recover dysfunctions within mitochondria. Fasting blood glucose and invasive left ventricular hemodynamic analysis confirmed the absence of type 2 diabetes and diabetic cardiomyopathy. However, fibrosis was already increased (P<0.05) ~70% in ZDF rats at this early stage in disease progression. Assessments of mitochondrial ADP and pyruvate respiratory kinetics in permeabilized fibres from the left ventricle revealed normal electron transport chain function and content. In contrast, the apparent Km to palmitoyl-CoA (P-CoA) was increased (P<0.05) ~60%, which was associated with an accumulation of intracellular triacylgycerol, diacylglycerol and ceramide species. In addition, the capacity for mitochondrial ROS emission was increased (P<0.05) ~3-fold in ZDF rats. The provision of resveratrol recovered fibrosis, P-CoA respiratory sensitivity, reactive lipid accumulation and mitochondrial reactive oxygen species emission rates. Altogether the current data supports the supposition that a chronic dysfunction within mitochondrial lipid-supported bioenergetics contributes to the development of diabetic cardiomyopathy, as this was present before overt diabetes or cardiac dysfunction. In addition, we show resveratrol supplementation prevents these changes, supporting the belief that resveratrol is a potent therapeutic approach for preventing diabetic cardiomyopathy.ic approach for preventing diabetic cardiomyopathy.)
Lores-Arnaiz 2016 Neurochem Res + (Alterations in mitochondrial bioenergetics … Alterations in mitochondrial bioenergetics have been associated with brain aging. In order to evaluate the susceptibility of brain cortex synaptosomes and non-synaptic mitochondria to aging-dependent dysfunction, male Swiss mice of 3 or 17 months old were used. Mitochondrial function was evaluated by oxygen consumption, mitochondrial membrane potential and respiratory complexes activity, together with UCP-2 protein expression. Basal respiration and respiration driving proton LEAK were decreased by 26 and 33 % in synaptosomes from 17-months old mice, but spare respiratory capacity was not modified by aging. Succinate supported state 3 respiratory rate was decreased by 45 % in brain cortex non-synaptic mitochondria from 17-month-old mice, as compared with young animals, but respiratory control was not affected. Synaptosomal mitochondria would be susceptible to undergo calcium-induced depolarization in 17 months-old mice, while non-synaptic mitochondria would not be affected by calcium overload. UCP-2 was significantly up-regulated in both synaptosomal and submitochondrial membranes from 17-months old mice, compared to young animals. UCP-2 upregulation seems to be a possible mechanism by which mitochondria would be resistant to suffer oxidative damage during aging.t to suffer oxidative damage during aging.)
Fahlbusch 2022 Int J Mol Sci + (Alterations in mitochondrial function are … Alterations in mitochondrial function are an important control variable in the progression of metabolic dysfunction-associated fatty liver disease (MAFLD), while also noted by increased de novo lipogenesis (DNL) and hepatic insulin resistance. We hypothesized that the organization and function of a mitochondrial electron transport chain (ETC) in this pathologic condition is a consequence of shifted substrate availability. We addressed this question using a transgenic mouse model with increased hepatic insulin resistance and DNL due to constitutively active human SREBP-1c. The abundance of ETC complex subunits and components of key metabolic pathways are regulated in the liver of these animals. Further omics approaches combined with functional assays in isolated liver mitochondria and primary hepatocytes revealed that the SREBP-1c-forced fatty liver induced a substrate limitation for oxidative phosphorylation, inducing enhanced complex II activity. The observed increased expression of mitochondrial genes may have indicated a counteraction. In conclusion, a shift of available substrates directed toward activated DNL results in increased electron flows, mainly through complex II, to compensate for the increased energy demand of the cell. The reorganization of key compounds in energy metabolism observed in the SREBP-1c animal model might explain the initial increase in mitochondrial function observed in the early stages of human MAFLD.served in the early stages of human MAFLD.)
Huetter 2006 Exp Gerontol + (Alterations in mitochondrial function are … Alterations in mitochondrial function are believed to play a major role in aging processes in many species, including fungi and animals, and increased oxidative stress is considered a major consequence of altered mitochondrial function. In support of this theory, a lot of correlative evidence has been collected, suggesting that changes in mitochondrial DNA accumulate with age in certain tissues. Furthermore, genetic experiments from lower eukaryotic model organisms, indicate a strong correlative link between increased resistance to oxidative stress and an extended lifespan; in addition, limited experimental evidence suggests that the inhibition of mitochondrial function by selected pharmacologically active compounds can extend lifespan in certain species. However, changes in mitochondrial function may affect aging in a different way in various tissues, and a clear statement about the role of mitochondrial deterioration during physiological aging is missing for most if not all species.At this point, respirometric analyses of mitochondrial function provide a tool to study age-associated changes in mitochondrial respiratory chain function and mitochondrial ATP production within living cells and isolated mitochondria. In the recent years, new instruments have been developed, which allow for an unprecedented high-resolution respirometry, which enables us to determine many parameters of mitochondrial function in routine assays using small samples of biological material. It is conceivable that this technology will become an important tool for all those, who are interested in experimentally addressing the mitochondrial theory of aging. In this article, we provide a synopsis of traditional respirometry and the advances of modern high-resolution respirometry, and discuss how future applications of this technology to recentlyestablished experimental models in aging research may provide exciting new insights into the role of mitochondria in the aging process.role of mitochondria in the aging process.)
Harmuth 2018 Front Mol Neurosci + (Alterations in mitochondrial morphology an … Alterations in mitochondrial morphology and function have been linked to neurodegenerative diseases, including Parkinson disease, Alzheimer disease and Huntington disease. Metabolic defects, resulting from dysfunctional mitochondria, have been reported in patients and respective animal models of all those diseases. Spinocerebellar Ataxia Type 3 (SCA3), another neurodegenerative disorder, also presents with metabolic defects and loss of body weight in early disease stages although the possible role of mitochondrial dysfunction in SCA3 pathology is still to be determined. Interestingly, the SCA3 disease protein ataxin-3, which is predominantly localized in cytoplasm and nucleus, has also been associated with mitochondria in both its mutant and wildtype form. This observation provides an interesting link to a potential mitochondrial involvement of mutant ataxin-3 in SCA3 pathogenesis. Furthermore, proteolytic cleavage of ataxin-3 has been shown to produce toxic fragments and even overexpression of artificially truncated forms of ataxin-3 resulted in mitochondria deficits. Therefore, we analyzed the repercussions of expressing a naturally occurring N-terminal cleavage fragment of ataxin-3 and the influence of an endogenous expression of the S256 cleavage fragment ''in vitro'' and ''in vivo''. In our study, expression of a fragment derived from calpain cleavage induced mitochondrial fragmentation and cristae alterations leading to a significantly decreased capacity of mitochondrial respiration and contributing to an increased susceptibility to apoptosis. Furthermore, analyzing mitophagy revealed activation of autophagy in the early pathogenesis with reduced lysosomal activity. In conclusion, our findings indicate that cleavage of ataxin-3 by calpains results in fragments which interfere with mitochondrial function and mitochondrial degradation processes.n and mitochondrial degradation processes.)
Buck 2017 PLOS ONE + (Alterations in mitochondrial respiration a … Alterations in mitochondrial respiration are an important hallmark of Huntington's disease (HD), one of the most common monogenetic causes of neurodegeneration. The ubiquitous expression of the disease causing mutant huntingtin gene raises the prospect that mitochondrial respiratory deficits can be detected in skeletal muscle. While this tissue is readily accessible in humans, transgenic animal models offer the opportunity to cross-validate findings and allow for comparisons across organs, including the brain. The integrated respiratory chain function of the human ''vastus lateralis'' muscle was measured by high-resolution respirometry (HRR) in freshly taken fine-needle biopsies from seven pre-manifest HD expansion mutation carriers and nine controls. The respiratory parameters were unaffected. For comparison skeletal muscle isolated from HD knock-in mice (HdhQ111) as well as a broader spectrum of tissues including cortex, liver and heart muscle were examined by HRR. Significant changes of mitochondrial respiration in the HdhQ knock-in mouse model were restricted to the liver and the cortex. Mitochondrial mass as quantified by mitochondrial DNA copy number and citrate synthase activity was stable in murine HD-model tissue compared to control. mRNA levels of key enzymes were determined to characterize mitochondrial metabolic pathways in HdhQ mice. We demonstrated the feasibility to perform high-resolution respirometry measurements from small human HD muscle biopsies. Furthermore, we conclude that alterations in respiratory parameters of pre-manifest human muscle biopsies are rather limited and mirrored by a similar absence of marked alterations in HdhQ skeletal muscle. In contrast, the HdhQ111 murine cortex and liver did show respiratory alterations highlighting the tissue specific nature of mutant huntingtin effects on respiration. mutant huntingtin effects on respiration.)
Ekbal 2013 Chest + (Alterations in oxygen transport and use ar … Alterations in oxygen transport and use are integral to the development of multiple organ failure; therefore, the ultimate goal of resuscitation is to restore effective tissue oxygenation and cellular metabolism. Hemodynamic monitoring is the cornerstone of management to promptly identify and appropriately manage (impending) organ dysfunction. Prospective randomized trials have confirmed outcome benefit when preemptive or early treatment is directed toward maintaining or restoring adequate tissue perfusion. However, treatment end points remain controversial, in large part because of current difficulties in determining what constitutes "optimal." Information gained from global whole-body monitoring may not detect regional organ perfusion abnormalities until they are well advanced. Conversely, the ideal "canary" organ that is readily accessible for monitoring, yet offers an early and sensitive indicator of tissue "unwellness," remains to be firmly identified. This review describes techniques available for real-time monitoring of tissue perfusion and metabolism and highlights novel developments that may complement or even supersede current tools.omplement or even supersede current tools.)
Schaefer 2017 Neurophotonics + (Alterations of cellular bioenergetics are … Alterations of cellular bioenergetics are a common feature in most neurodegenerative disorders. However, there is a selective vulnerability of different brain regions, cell types, and even mitochondrial populations to these metabolic disturbances. Thus, the aim of our study was to establish and validate an ''in vivo'' metabolic imaging technique to screen for mitochondrial function on the subcellular level. Based on nicotinamide adenine dinucleotide (phosphate) fluorescence lifetime imaging microscopy [NAD(P)H FLIM], we performed a quantitative correlation to high-resolution respirometry. Thereby, we revealed mitochondrial matrix pH as a decisive factor in imaging NAD(P)H redox state. By combining both parameters, we illustrate a quantitative, high-resolution assessment of mitochondrial function in metabolically modified cells as well as in an amyloid precursor protein-overexpressing model of Alzheimer's disease. Our metabolic imaging technique provides the basis for dissecting mitochondrial deficits not only in a range of neurodegenerative diseases, shedding light onto bioenergetic failures of cells remaining in their metabolic microenvironment.ining in their metabolic microenvironment.)
Koliaki 2013 Mol Cell Endocrinol + (Alterations of hepatic mitochondrial funct … Alterations of hepatic mitochondrial function have been observed in states of insulin resistance and non-alcoholic fatty liver disease (NAFLD). Patients with overt type 2 diabetes mellitus (T2DM) can exhibit reduction in hepatic adenosine triphosphate (ATP) synthesis and impaired repletion of their hepatic ATP stores upon ATP depletion by fructose. Obesity and NAFLD may also associate with impaired ATP recovery after ATP-depleting challenges and augmented oxidative stress in the liver. On the other hand, patients with obesity or NAFLD can present with upregulated hepatic anaplerotic and oxidative fluxes, including β-oxidation and tricarboxylic cycle activity. The present review focuses on the methods and data on hepatic energy metabolism in various states of human insulin resistance. We propose that the liver can adapt to increased lipid exposition by greater lipid storing and oxidative capacity, resulting in increased oxidative stress, which in turn could deteriorate hepatic mitochondrial function in chronic insulin resistance and NAFLD.n in chronic insulin resistance and NAFLD.)
Fazzini 2016 Abstract Mito Xmas Meeting Innsbruck + (Alterations of mitochondrial DNA (mtDNA) c … Alterations of mitochondrial DNA (mtDNA) copy number appear to be associated with several pathologies including encephalopathies and neuropathies as well as the process of aging [1-2].The aim of this study was to set up a reliable quantitative PCR based assay for mitochondrial DNA copy number determination meeting quality requirements for mtDNA specificity.We established a duplex quantitative PCR assay that allows for targeting a single copy nuclear gene (ß2-microglobulin) and the mtDNA (t-RNA Leu) simultaneously. The use of a plasmid containing both targets in a 1:1 ratio was used to normalize against differences in emission intensities of the fluorescent dyes VIC and FAM. QPCR on the serial dilution of the calibrator plasmid revealed that the FAM dye emission signal exceeded the VIC signal, resulting in a ΔCT value of up to 1.2 cycles corresponding to more than a double amount of molecules. Using the plasmid calibrator with internal positive controls reduced the intra-assay variability from 21% (uncorrected) to 7% (plasmid corrected). We evaluated the applicability of the method by using DNA samples that were isolated with different methods and revealed significantly different numbers of mtDNA copies (copy number ratio: salting out/magnetic beads = 1.65).We developed a sensitive and robust assay for mitochondrial copy number detection relative to nuclear DNA. The use of the dual insert calibrator plasmid allows for correction against unequal emission intensities of the differently fluorescence labelled targets. Furthermore, we discovered that the diverse extraction methods selectively isolate different DNA molecules within a sample.e different DNA molecules within a sample.)
Pak 2013 Am J Respir Cell Mol Biol + (Alterations of mitochondrial membrane pote … Alterations of mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and mitochondrial respiration are possible triggers of pulmonary vascular remodeling in pulmonary hypertension (PH). We investigated the role of MMP in PH and hypothesized that deletion of the mitochondrial uncoupling protein 2 (UCP2) increases MMP, thus promoting pulmonary vascular remodeling and PH. MMP was measured by JC-1 in isolated pulmonary arterial smooth muscle cells (PASMCs) of patients with PH and animals with PH induced by exposure to monocrotaline (MCT) or chronic hypoxia. PH was quantified ''in vivo'' in UCP2-deficient (UCP2(-/-)) mice by hemodynamics, morphometry, and echocardiography. ROS were measured by electron spin resonance spectroscopy and proliferation by thymidine incorporation. Mitochondrial respiration was investigated by high-resolution respirometry. MMP was increased in PASMCs of patients and in animal models of PH. UCP2(-/-) mice exhibited pulmonary vascular remodeling and mild PH compared with wild-type (WT) mice. PASMCs of UCP2(-/-) mice showed increased proliferation, MMP, and ROS release. Increased proliferation of UCP2(-/-) PASMCs could be attenuated by ROS inhibitors and inhibited by carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone, which decreased MMP to the level of WT mice. Mitochondrial respiration was altered in PASMCs from MCT rats and PASMCs exposed to hypoxia but not in isolated pulmonary mitochondria of UCP2(-/-) mice or PASMCs after treatment with small interfering RNA for UCP2. Our data suggest that increased MMP causes vascular remodeling in UCP2(-/-) mice partially via increased ROS. In chronic hypoxia and MCT-induced PH, additional pathomechanisms such as decreased respiration may play a role. as decreased respiration may play a role.)
Goldberg 2019 Biochem J + (Alterations to branched-chain keto acid (B … Alterations to branched-chain keto acid (BCKA) oxidation have been implicated in a wide variety of human diseases, ranging from diabetes to cancer. Although global shifts in BCKA metabolism-evident by gene transcription, metabolite profiling, and ''in vivo'' flux analyses have been documented across various pathological conditions, the underlying biochemical mechanism(s) within the mitochondrion remain largely unknown. ''In vitro'' experiments using isolated mitochondria represent a powerful biochemical tool for elucidating the role of the mitochondrion in driving disease. Such analyses have routinely been utilized across disciplines to shed valuable insight into mitochondrial-linked pathologies. That said, few studies have attempted to model ''in vitro'' BCKA oxidation in isolated organelles. The impetus for the present study stemmed from the knowledge that complete oxidation of each of the three BCKAs involves a reaction dependent upon bicarbonate and ATP, both of which are not typically included in respiration experiments. Based on this, it was hypothesized that the inclusion of exogenous bicarbonate and stimulation of respiration using physiological shifts in ATP-free energy, rather than excess ADP, would allow for maximal BCKA-supported respiratory flux in isolated mitochondria. This hypothesis was confirmed in mitochondria from several mouse tissues, including heart, liver and skeletal muscle. What follows is a thorough characterization and validation of a novel biochemical tool for investigating BCKA metabolism in isolated mitochondria.© 2019 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.ed on behalf of the Biochemical Society.)
Goldberg 2021 Biochem J + (Alterations to branched-chain keto acid (B … Alterations to branched-chain keto acid (BCKA) oxidation have been implicated in a wide variety of human diseases, ranging from diabetes to cancer. Although global shifts in BCKA metabolism-evident by gene transcription, metabolite profiling, and ''in vivo'' flux analyses have been documented across various pathological conditions, the underlying biochemical mechanism(s) within the mitochondrion remain largely unknown. ''In vitro'' experiments using isolated mitochondria represent a powerful biochemical tool for elucidating the role of the mitochondrion in driving disease. Such analyses have routinely been utilized across disciplines to shed valuable insight into mitochondrial-linked pathologies. That said, few studies have attempted to model ''in vitro'' BCKA oxidation in isolated organelles. The impetus for the present study stemmed from the knowledge that complete oxidation of each of the three BCKAs involves a reaction dependent upon bicarbonate and ATP, both of which are not typically included in respiration experiments. Based on this, it was hypothesized that the inclusion of exogenous bicarbonate and stimulation of respiration using physiological shifts in ATP-free energy, rather than excess ADP, would allow for maximal BCKA-supported respiratory flux in isolated mitochondria. This hypothesis was confirmed in mitochondria from several mouse tissues, including heart, liver and skeletal muscle. What follows is a thorough characterization and validation of a novel biochemical tool for investigating BCKA metabolism in isolated mitochondria. BCKA metabolism in isolated mitochondria.)
Fisar 2019 Clin Biochem + (Altered amyloid metabolism and mitochondri … Altered amyloid metabolism and mitochondrial dysfunction play key roles in the development of Alzheimer's disease (AD). We asked whether an association exists between disturbed platelet mitochondrial respiration and the plasma concentrations of Aβ40 and Aβ42 in patients with AD.Plasma Aβ40 and Aβ42 concentrations and mitochondrial respiration in intact and permeabilized platelets were measured in 50 patients with AD, 15 patients with vascular dementia and 25 control subjects. A pilot longitudinal study was performed to monitor the progression of AD in a subgroup 11 patients with AD.The mean Aβ40, Aβ42 and Aβ42/Aβ40 levels were not significantly altered in patients with AD compared with controls. The mitochondrial respiratory rate in intact platelets was significantly reduced in patients with AD compared to controls, particularly the basal respiratory rate, maximum respiratory capacity, and respiratory reserve; however, the flux control ratio for basal respiration was increased. A correlation between the plasma Aβ42 concentration and mitochondrial respiration in both intact and permeabilized platelets differs in controls and patients with AD.Based on our data, (1) mitochondrial respiration in intact platelets, but not the Aβ level itself, may be included in a panel of biomarkers for AD; (2) dysfunctional mitochondrial respiration in platelets is not explained by changes in plasma Aβ concentrations; and (3) the association between mitochondrial respiration in platelets and plasma Aβ levels differs in patients with AD and controls. The results supported the hypothesis that mitochondrial dysfunction is the primary factor contributing to the development of AD.Copyright © 2019. Published by Elsevier Inc.at mitochondrial dysfunction is the primary factor contributing to the development of AD. Copyright © 2019. Published by Elsevier Inc.)
Chowdhury 2018 Oxid Med Cell Longev + (Altered cellular metabolism is considered … Altered cellular metabolism is considered a hallmark of cancer and is fast becoming an avenue for therapeutic intervention. Mitochondria have recently been viewed as an important cellular compartment that fuels the metabolic demands of cancer cells. Mitochondria are the major source of ATP and metabolites necessary to fulfill the bioenergetics and biosynthetic demands of cancer cells. Furthermore, mitochondria are central to cell death and the main source for generation of reactive oxygen species (ROS). Overall, the growing evidence now suggests that mitochondrial bioenergetics, biogenesis, ROS production, and adaptation to intrinsic oxidative stress are elevated in chronic lymphocytic leukemia (CLL). Hence, recent studies have shown that mitochondrial metabolism could be targeted for cancer therapy. This review focuses the recent advancements in targeting mitochondrial metabolism for the treatment of CLL.drial metabolism for the treatment of CLL.)
Schoepf 2016 FEBS J + (Altered mitochondrial metabolism plays a p … Altered mitochondrial metabolism plays a pivotal role in the development and progression of various diseases, including cancer. Cell lines are frequently used as models to study mitochondrial (dys)function but little is known about their mitochondrial respiration and metabolic properties in comparison to the primary tissue of origin. We have developed a method for assessment of oxidative phosphorylation in prostate tissue samples of only 2 mg wet weight using high-resolution respirometry. Reliable protocols were established to investigate the respiratory activity of different segments of the mitochondrial electron transfer-pathway in mechanically permeabilized tissue biopsies. Additionally, the widely used immortalized prostate epithelial and fibroblast cell lines RWPE1 and NAF, representing the major cell types in prostate tissue, were analyzed and compared to the tissue of origin. Our results show that mechanical treatment without chemical permeabilization agents or sample processing constitutes a reliable preparation method for OXPHOS analysis in small amounts of prostatic tissue typically obtained by prostate biopsy. The cell lines represented the bioenergetic properties of fresh tissue to a limited extent only. Particularly, tissue showed a higher oxidative capacity with succinate and glutamate, whereas pyruvate was a substrate supporting significantly higher respiratory activities in cell lines. Several fold higher zinc levels measured in tissue compared to cells confirmed the role of aconitase for prostate specific metabolism in agreement with observed respiratory properties. In conclusion, combining the flexibility of cell culture models and tissue samples for respirometric analysis are powerful tools for investigation of mitochondrial function and tissue specific metabolism. n and tissue specific metabolism. )
Kupats 2020 Oxid Med Cell Longev + (Altered neuronal Ca2+</sup&g … Altered neuronal Ca2+ homeostasis and mitochondrial dysfunction play a central role in the pathogenesis of traumatic brain injury (TBI). R-Phenibut ((3R)-phenyl-4-aminobutyric acid) is an antagonist of the α2δ subunit of voltage-dependent calcium channels (VDCC) and an agonist of gamma-aminobutyric acid B (GABA-B) receptors. The aim of this study was to evaluate the potential therapeutic effects of R-phenibut following the lateral fluid percussion injury (latFPI) model of TBI in mice and the impact of R- and S-phenibut on mitochondrial functionality ''in vitro''. By determining the bioavailability of R-phenibut in the mouse brain tissue and plasma, we found that R-phenibut (50 mg/kg) reached the brain tissue 15 min after intraperitoneal (i.p.) and peroral (p.o.) injections. The maximal concentration of R-phenibut in the brain tissues was 0.6 μg/g and 0.2 μg/g tissue after i.p. and p.o. administration, respectively. Male Swiss-Webster mice received i.p. injections of R-phenibut at doses of 10 or 50 mg/kg 2 h after TBI and then once daily for 7 days. R-Phenibut treatment at the dose of 50 mg/kg significantly ameliorated functional deficits after TBI on postinjury days 1, 4, and 7. Seven days after TBI, the number of Nissl-stained dark neurons (N-DNs) and interleukin-1beta (IL-1β) expression in the cerebral neocortex in the area of cortical impact were reduced. Moreover, the addition of R- and S-phenibut at a concentration of 0.5 μg/ml inhibited calcium-induced mitochondrial swelling in the brain homogenate and prevented anoxia-reoxygenation-induced increases in mitochondrial H2O2 production and the H2O2/O ratio. Taken together, these results suggest that R-phenibut could serve as a neuroprotective agent and promising drug candidate for treating TBI.erve as a neuroprotective agent and promising drug candidate for treating TBI.)
Porter 2015 Burns + (Altered skeletal muscle mitochondrial func … Altered skeletal muscle mitochondrial function contributes to the pathophysiological stress response to burns. However, the acute and chronic impact of burn trauma on skeletal muscle bioenergetics remains poorly understood. Here, we determined the temporal relationship between burn trauma and mitochondrial function in murine skeletal muscle local to and distal from burn wounds. Male BALB/c mice (8-10 weeks old) were burned by submersion of the dorsum in water (∼95°C) to create a full thickness burn on ∼30% of the body. Skeletal muscle was harvested spinotrapezius underneath burn wounds (local) and the quadriceps (distal) of sham and burn treated mice at 3h, 24h, 4d and 10d post-injury. Mitochondrial respiration was determined in permeabilized myofiber bundles by high-resolution respirometry. Caspase 9 and caspase 3 protein concentration were determined by western blot. In muscle local to burn wounds, respiration coupled to ATP production was significantly diminished at 3h and 24h post-injury (''P''<0.001), as was mitochondrial coupling control (''P''<0.001). There was a 5- (''P''<0.05) and 8-fold (''P''<0.001) increase in respiration in response to cytochrome at 3h and 24h post burn, respectively, indicating damage to the outer mitochondrial membranes. Moreover, we also observed greater active caspase 9 and caspase 3 in muscle local to burn wounds, indicating the induction of apoptosis. Distal muscle mitochondrial function was unaltered by burn trauma until 10d post burn, where both respiratory capacity (''P''<0.05) and coupling control (''P''<0.05) were significantly lower than sham. These data highlight a differential response in muscle mitochondrial function to burn trauma, where the timing, degree and mode of dysfunction are dependent on whether the muscle is local or distal to the burn wound. on whether the muscle is local or distal to the burn wound.)
Krischek 2016 Mol Reprod Dev + (Altering incubation temperature during emb … Altering incubation temperature during embryogenesis has an impact on chicken embryo growth, but the underlying molecular mechanisms are not understood; the present study was performed to address these changes. Broiler eggs were incubated at low (36.8°C), control (37.8°C), and high (38.8°C) temperatures between Embryonic Day (ED) 7 and 10 or ED 10 and 13, which cover critical periods of embryonic myogenesis. The embryos were then dissected immediately after treatment on ED 10 or 13 to assess body, liver, and heart weights as well as to analyze breast and leg muscle fibers for their mitochondrial respiratory activity (MRA). Breast muscle samples were additionally used to evaluate the activity of enzymes involved in energy metabolism and cell-cycle progression. ED-10 embryos incubated at 38.8°C showed elevated weights (body, liver, and heart), MRA, and activities of lactate dehydrogenase and cytochrome oxidase compared to the ED-10 embryos incubated at 36.8°C. Similarly, the ED-13 embryos incubated at 38.8°C showed elevated body weight, MRA, and activities of glycogen phosphorylase, phosphofructokinase, and cytochrome oxidase compared to their 36.8°C counterparts. Embryos incubated at the normal temperature (37.8°C), however, showed variable differences from those incubated at 38.8°C versus 36.8°C. Cell-cycle enzyme activities were not impacted by the different temperature treatments. Thus, an increase or decrease in the incubation temperature during embryonic broiler myogenesis results in altered embryo activity, muscle energy metabolism, and activity-dependent muscle growth.ism, and activity-dependent muscle growth.)
Oparka 2014 Abstract MiP2014 + (Alternations of pivotal mitochondrial func … Alternations of pivotal mitochondrial function – oxidative phosphorylation as well as abnormal cellular ROS production - can potentially be responsible for pathogenesis of cancer. In the last years, implications of p66Shc adaptor protein in the cellular response to oxidative stress have been discovered. Involvement of this protein in cell death is related to oxidative stress. Phosphorylation of p66Shc at Ser36 can be activated by extracellular or intracellular reactive oxygen species (ROS), and an initiated cascade of events is finally involved in the amplification of mitochondrial ROS production. The available literature does not contain a lot of data concerning the role of p66shc and its Ser36 phosphorylation in tumorigenesis and cancer growth. Therefore, we studied the relationship between ROS production, antioxidant defense systems and the level of p66Shc as well as p66Shc phosphorylation in murine cancer cell lines, derived from ectoderm (B16-F10, B78, MmB16, EMT6, 4T1), mesoderm (Renca) and endoderm (CT26.WT, Hepa1-6, LLC, Panc02).The cancer cells exhibited various levels of p66Shc and its Ser36 phosphorylation, which simultaneously is negatively correlated with the level of superoxide dismutase 2 in some of the investigated cancer cell lines. ROS can mediate opposing cellular functions like cell proliferation and apoptosis. In turn, p66Shc Ser36 phosphorylation pathway is involved in regulation of mitochondrial metabolism and is responsible for elevated intracellular ROS levels. Moreover, p66Shc seems to play an important role in cancer metastasis and cancer cell adhesion. This emphasizes the importance of understanding the mechanisms and sites of ROS formation in cancer cells, the role of p66Shc in this process and the effect on tumor physiology.Supported by Statutory Founding from Nencki Institute of Experimental Biology and Polish Ministry of Science and Higher Education grant W100/HFSC/2011.and Higher Education grant W100/HFSC/2011.)
Polajnar 2014 PLOS ONE + (Alternative functions, apart from cathepsi … Alternative functions, apart from cathepsins inhibition, are being discovered for stefin B. Here, we investigate its role in vesicular trafficking and autophagy. Astrocytes isolated from stefin B knock-out (KO) mice exhibited an increased level of protein aggregates scattered throughout the cytoplasm. Addition of stefin B monomers or small oligomers to the cell medium reverted this phenotype, as imaged by confocal microscopy. To monitor the identity of proteins embedded within aggregates in wild type (wt) and KO cells, the insoluble cell lysate fractions were isolated and analyzed by mass spectrometry. Chaperones, tubulins, dyneins, and proteosomal components were detected in the insoluble fraction of wt cells but not in KO aggregates. In contrast, the insoluble fraction of KO cells exhibited increased levels of apolipoprotein E, fibronectin, clusterin, major prion protein, and serpins H1 and I2 and some proteins of lysosomal origin, such as cathepsin D and CD63, relative to wt astrocytes. Analysis of autophagy activity demonstrated that this pathway was less functional in KO astrocytes. In addition, synthetic dosage lethality (SDL) gene interactions analysis in ''Saccharomyces cerevisiae'' expressing human stefin B suggests a role in transport of vesicles and vacuoles These activities would contribute, directly or indirectly to completion of autophagy in wt astrocytes and would account for the accumulation of protein aggregates in KO cells, since autophagy is a key pathway for the clearance of intracellular protein aggregates.rance of intracellular protein aggregates.)
Rajendran 2019 EMBO Mol Med + (Alternative oxidase (AOX) is a non-mammali … Alternative oxidase (AOX) is a non-mammalian enzyme that can bypass blockade of the complex III-IV segment of the respiratory chain (RC). We crossed a Ciona intestinalis AOX transgene into RC complex III (cIII)-deficient Bcs1lp.S78G knock-in mice, displaying multiple visceral manifestations and premature death. The homozygotes expressing AOX were viable, and their median survival was extended from 210 to 590 days due to permanent prevention of lethal cardiomyopathy. AOX also prevented renal tubular atrophy and cerebral astrogliosis, but not liver disease, growth restriction, or lipodystrophy, suggesting distinct tissue-specific pathogenetic mechanisms. Assessment of reactive oxygen species (ROS) production and damage suggested that ROS were not instrumental in the rescue. Cardiac mitochondrial ultrastructure, mitochondrial respiration, and pathological transcriptome and metabolome alterations were essentially normalized by AOX, showing that the restored electron flow upstream of cIII was sufficient to prevent cardiac energetic crisis and detrimental decompensation. These findings demonstrate the value of AOX, both as a mechanistic tool and a potential therapeutic strategy, for cIII deficiencies.© 2018 The Authors. Published under the terms of the CC BY 4.0 license. Published under the terms of the CC BY 4.0 license.)
Robertson 2016 J Bioenerg Biomembr + (Alternative oxidase (AOX) is a terminal ox … Alternative oxidase (AOX) is a terminal oxidase within the inner mitochondrial membrane (IMM) present in many organisms where it functions in the electron transport system (ET-pathway). AOX directly accepts electrons from ubiquinol and is therefore capable of bypassing ET-pathway Complexes III and IV. The human genome does not contain a gene coding for AOX, so AOX expression has been suggested as a gene therapy for a range of human mitochondrial diseases caused by genetic mutations that render Complex III and/or IV dysfunctional. An effective means of screening mutations amenable to AOX treatment remains to be devised. We have generated such a tool by heterologously expressing AOX from the Pacific oyster (''Crassostrea gigas'') in the yeast ''Saccharomyces cerevisiae'' under the control of a galactose promoter. Our results show that this animal AOX is monomeric and is correctly targeted to yeast mitochondria. Moreover, when expressed in yeast, Pacific oyster AOX is a functional quinol oxidase, conferring cyanide-resistant growth and myxothiazol-resistant oxygen consumption to yeast cells and isolated mitochondria. This system represents a high-throughput screening tool for determining which Complex III and IV genetic mutations in yeast will be amenable to AOX gene therapy. As many human genes are orthologous to those found in yeast, our invention represents an efficient and cost-effective way to evaluate viable research avenues. In addition, this system provides the opportunity to learn more about the localization, structure, and regulation of AOXs from animals that are not easily reared or manipulated in the lab.t easily reared or manipulated in the lab.)
McDonald 2011 Abstract IOC65 + (Alternative oxidase (AOX) is a ubiquinol t … Alternative oxidase (AOX) is a ubiquinol terminal oxidase present in the respiratory electron transport chains of a wide variety of organisms [1]. AOX by-passes 2 of the 3 proton pumping complexes in the respiratory chain and therefore makes respiration less efficient in terms of the amount of ATP generated per oxygen consumed. Our previous work using bioinformatics has revealed the presence of AOX genes in eukaryotic organisms such as plants, animals, fungi, algae, and protists, as well as in prokaryotes in several species of eubacteria [2]. Recent work using reverse transcriptase polymerase chain reaction (RT-PCR) experiments has demonstrated that these genes are transcribed in many organisms [3]. Our focus is now shifting to exploring the respiratory capacity of AOX proteins in these different systems and in identifying how the activity of AOX proteins is regulated at the post-translational level.regulated at the post-translational level.)
Dogan 2018 Cell Metab + (Alternative oxidases (AOXs) bypass respira … Alternative oxidases (AOXs) bypass respiratory complexes III and IV by transferring electrons from coenzyme Q directly to O2. They have therefore been proposed as a potential therapeutic tool for mitochondrial diseases. We crossed the severely myopathic skeletal muscle-specific COX15 knockout (KO) mouse with an AOX-transgenic mouse. Surprisingly, the double KO-AOX mutants had decreased lifespan and a substantial worsening of the myopathy compared with KO alone. Decreased ROS production in KO-AOX versus KO mice led to impaired AMPK/PGC-1α signaling and PAX7/MYOD-dependent muscle regeneration, blunting compensatory responses. Importantly, the antioxidant N-acetylcysteine had a similar effect, decreasing the lifespan of KO mice. Our findings have major implications for understanding pathogenic mechanisms in mitochondrial diseases and for the design of therapies, highlighting the benefits of ROS signaling and the potential hazards of antioxidant treatment.ng and the potential hazards of antioxidant treatment.)
Moreno-Ortega 2016 Neurotox Res + (Alternatives for the treatment of amyotrop … Alternatives for the treatment of amyotrophic lateral sclerosis (ALS) are scarce and controversial. The etiology of neuronal vulnerability in ALS is being studied in motor neuron-like NSC-34 cells to determine the underlying mechanisms leading to selective loss of motor neurons. One such mechanism is associated with mitochondrial oxidative stress, Ca2+ overload, and low expression of Ca2+-buffering proteins. Therefore, in order to elicit neuronal death in ALS, NSC-34 cells were exposed to the following cytotoxic agents: (1) a mixture of oligomycin 10 µM and rotenone 30 µM (O/R), or (2) phenylarsine oxide 1 µM (PAO) (to mimic excess free radical production during mitochondrial dysfunction), and (3) veratridine 100 µM (VTD) (to induce overload of Na(+) and Ca2+ and to alter distribution of Ca2+-buffering proteins [parvalbumin and calbindin-D28k]). Thus, the aim of the study was to test the novel neuroprotective compound ITH33/IQM9.21 (ITH33) and to compare it with riluzole on ''in vitro'' models of neurotoxicity. Cell viability measured with MTT showed that only ITH33 protected against O/R at 3 μM and PAO at 10 μM, but not riluzole. ITH33 and riluzole were neuroprotective against VTD, blocked the maximum peak and the number of [Ca2+]c oscillations per cell, and restored the effect on parvalbumin. However, only riluzole reversed the effect on calbindin-D28k levels. Therefore, ITH33 was neuroprotective against oxidative stress and Na+/Ca2+ overload, both of which are involved in ALS.ainst oxidative stress and Na+/Ca2+ overload, both of which are involved in ALS.)
Irving 2022 Abstract Bioblast + (Although Alzheimer's disease (AD)'s underl … Although Alzheimer's disease (AD)'s underlying pathophysiology is incompletely understood, reductions in mitochondrial bioenergetics are observed during AD development. Reductions in nitric oxide (NO) bioavailability can reduce cerebral blood flow, promote the deposition of β-amyloid (Aβ), and contribute to mitochondrial dysfunction. However, pathological elevations in NO can also inhibit mitochondrial respiration and mitochondrial quality control. High-Fat Diets (HFD) are associated with reductions in NO bioavailability and AD development. Therefore, we sought to investigate the effects of dietary NO donors (Na+-nitrite and citrulline) on mitochondrial bioenergetics in female APPswe/PS1dE9 (APP/PS1) fed a HFD.We fed 10-week-old APP/PS1 transgenic mice, and their littermate controls (wild-type, WT) either a normal chow diet, HFD, or HFD supplemented with a NO promoter (Na+-nitrite or L-citrulline) for six months. Specifically, 100 mg/L Na+-nitrite or 2.5 mM L-citrulline was provided in their drinking water. The mice were euthanized, and the hypothalami were carefully dissected out and placed in ice-cold BIOPS. The hypothalami were homogenized in a mitochondrial respiration media (MiR05-Kit, pH 7.1).We used high-resolution respirometry (HRR, Oroboros O2k) coupled with a standardized substrate-uncoupler-inhibitor-titration (SUIT) protocol to measure respiration rates in duplicate during LEAK (State 4), OXPHOS capacity (State 3), and electron transfer capacity (ET) states in permeabilized hypothalami homogenates at 37 °C and O2 concentrations between ~450 µM and ~150 µM. We supplement the MiR05 with α-chaconine (40 µM) to chemically permeabilize the plasma membranes and synaptosomes. First, we measured NADH-linked LEAK respiration (N''L'') in the presence of pyruvate (5 mM), malate (2 mM), and glutamate (10 mM) in the absence of ADP. We measured NADH-Linked OXPHOS (N''P'') following the addition of a saturating concentration of ADP-Mg++ (5 mM). Next, we assessed the mitochondrial membrane integrity using cytochrome ''c'' (10 µM). We measured NS-linked OXPHOS (NS''P'') after the addition of succinate (10 mM). Next, we titrated in carbonyl cyanide m-chlorophenyl hydrazine (CCCP) (0.5 µM/step) to achieve NS-linked ET capacity (NS''E''). Next, we titrated rotenone (0.5 µM) to measure succinate-linked ET capacity (S''E''), followed by the titration of glycerol-3-phosphate (15 mM) to measure SGp-linked ET capacity (SGp''E''). Finally, we added antimycin A (2.5 µM) to measure residual oxygen consumption (''Rox''). The respiration rates were normalized per mg mass [pmol·s-1·mg-1], referred to as oxygen flux (''J''O2).The final body and fat masses of HFD-fed APP/PS1 mice (48.2 g & 17.7 g) were significantly higher than those of HFD-fed WT mice (42.4 g & 14.3 g). NO donors (Na+-nitrite or citrulline) had no effect on body mass or fat mass. There was a significant group effect (''p''<0.05) effect on OXPHOS and ET capacity. Specifically, the APS/PS1 mice had significantly lower OXPHOS and ET capacity while on the HFD compared to WT. The NO donors (Na+-nitrite or citrulline) could rescue the OXPHOS and ET capacity in the APS/PS1 mice fed a HFD.In summary, the APS/PS1 mice had lower OXPHOS and ET capacity than their WT controls while on an HFD. Physiologically relevant NO donors may provide an opportunity to mitigate some of the negative consequences of AD pathology.n the APS/PS1 mice fed a HFD. In summary, the APS/PS1 mice had lower OXPHOS and ET capacity than their WT controls while on an HFD. Physiologically relevant NO donors may provide an opportunity to mitigate some of the negative consequences of AD pathology.)
Khrameeva 2014 Nat Commun + (Although Neanderthals are extinct, fragmen … Although Neanderthals are extinct, fragments of their genomes persist in contemporary humans. Here we show that while the genome-wide frequency of Neanderthal-like sites is approximately constant across all contemporary out-of-Africa populations, genes involved in lipid catabolism contain more than threefold excess of such sites in contemporary humans of European descent. Evolutionally, these genes show significant association with signatures of recent positive selection in the contemporary European, but not Asian or African populations. Functionally, the excess of Neanderthal-like sites in lipid catabolism genes can be linked with a greater divergence of lipid concentrations and enzyme expression levels within this pathway, seen in contemporary Europeans, but not in the other populations. We conclude that sequence variants that evolved in Neanderthals may have given a selective advantage to anatomically modern humans that settled in the same geographical areas.at settled in the same geographical areas.)